Character Flying around uncontrollably

I don't really know how to describe this phenominon but in the game I am working on myself and a couple friends have noticed that when running the game in a built version (Standalone) That the character (standard assets FPS Controller) will occasionally take off and start zipping around in the air in circles flying around the map uncontrollably. We seem to have narrowed this down to being when jumping down from a hieght (off a cliff, or going down the side of a mountain). Has anyone else ever experienced anything like this before? I am trying to find a spot that causes this to happen every time so I can video record it but so far no luck it seems very random. Any thoughts would help alot as this seems to be a major bug.

thanks.. Ajaxx

The script as per request.

 #pragma strict
 #pragma implicit
 #pragma downcast
 
 // Does this script currently respond to input?
 var canControl : boolean = true;
 
 var useFixedUpdate : boolean = true;
 
 // For the next variables, @System.NonSerialized tells Unity to not serialize the variable or show it in the inspector view.
 // Very handy for organization!
 
 // The current global direction we want the character to move in.
 @System.NonSerialized
 var inputMoveDirection : Vector3 = Vector3.zero;
 
 // Is the jump button held down? We use this interface instead of checking
 // for the jump button directly so this script can also be used by AIs.
 @System.NonSerialized
 var inputJump : boolean = false;
 
 class CharacterMotorMovement {
     // The maximum horizontal speed when moving
     var maxForwardSpeed : float = 10.0;
     var maxSidewaysSpeed : float = 10.0;
     var maxBackwardsSpeed : float = 10.0;
     
     // Curve for multiplying speed based on slope (negative = downwards)
     var slopeSpeedMultiplier : AnimationCurve = AnimationCurve(Keyframe(-90, 1), Keyframe(0, 1), Keyframe(90, 0));
     
     // How fast does the character change speeds?  Higher is faster.
     var maxGroundAcceleration : float = 30.0;
     var maxAirAcceleration : float = 20.0;
 
     // The gravity for the character
     var gravity : float = 10.0;
     var maxFallSpeed : float = 20.0;
     
     // For the next variables, @System.NonSerialized tells Unity to not serialize the variable or show it in the inspector view.
     // Very handy for organization!
 
     // The last collision flags returned from controller.Move
     @System.NonSerialized
     var collisionFlags : CollisionFlags; 
 
     // We will keep track of the character's current velocity,
     @System.NonSerialized
     var velocity : Vector3;
     
     // This keeps track of our current velocity while we're not grounded
     @System.NonSerialized
     var frameVelocity : Vector3 = Vector3.zero;
     
     @System.NonSerialized
     var hitPoint : Vector3 = Vector3.zero;
     
     @System.NonSerialized
     var lastHitPoint : Vector3 = Vector3(Mathf.Infinity, 0, 0);
 }
 
 var movement : CharacterMotorMovement = CharacterMotorMovement();
 
 enum MovementTransferOnJump {
     None, // The jump is not affected by velocity of floor at all.
     InitTransfer, // Jump gets its initial velocity from the floor, then gradualy comes to a stop.
     PermaTransfer, // Jump gets its initial velocity from the floor, and keeps that velocity until landing.
     PermaLocked // Jump is relative to the movement of the last touched floor and will move together with that floor.
 }
 
 // We will contain all the jumping related variables in one helper class for clarity.
 class CharacterMotorJumping {
     // Can the character jump?
     var enabled : boolean = true;
 
     // How high do we jump when pressing jump and letting go immediately
     var baseHeight : float = 1.0;
     
     // We add extraHeight units (meters) on top when holding the button down longer while jumping
     var extraHeight : float = 4.1;
     
     // How much does the character jump out perpendicular to the surface on walkable surfaces?
     // 0 means a fully vertical jump and 1 means fully perpendicular.
     var perpAmount : float = 0.0;
     
     // How much does the character jump out perpendicular to the surface on too steep surfaces?
     // 0 means a fully vertical jump and 1 means fully perpendicular.
     var steepPerpAmount : float = 0.5;
     
     // For the next variables, @System.NonSerialized tells Unity to not serialize the variable or show it in the inspector view.
     // Very handy for organization!
 
     // Are we jumping? (Initiated with jump button and not grounded yet)
     // To see if we are just in the air (initiated by jumping OR falling) see the grounded variable.
     @System.NonSerialized
     var jumping : boolean = false;
     
     @System.NonSerialized
     var holdingJumpButton : boolean = false;
 
     // the time we jumped at (Used to determine for how long to apply extra jump power after jumping.)
     @System.NonSerialized
     var lastStartTime : float = 0.0;
     
     @System.NonSerialized
     var lastButtonDownTime : float = -100;
     
     @System.NonSerialized
     var jumpDir : Vector3 = Vector3.up;
 }
 
 var jumping : CharacterMotorJumping = CharacterMotorJumping();
 
 class CharacterMotorMovingPlatform {
     var enabled : boolean = true;
     
     var movementTransfer : MovementTransferOnJump = MovementTransferOnJump.PermaTransfer;
     
     @System.NonSerialized
     var hitPlatform : Transform;
     
     @System.NonSerialized
     var activePlatform : Transform;
     
     @System.NonSerialized
     var activeLocalPoint : Vector3;
     
     @System.NonSerialized
     var activeGlobalPoint : Vector3;
     
     @System.NonSerialized
     var activeLocalRotation : Quaternion;
     
     @System.NonSerialized
     var activeGlobalRotation : Quaternion;
     
     @System.NonSerialized
     var lastMatrix : Matrix4x4;
     
     @System.NonSerialized
     var platformVelocity : Vector3;
     
     @System.NonSerialized
     var newPlatform : boolean;
 }
 
 var movingPlatform : CharacterMotorMovingPlatform = CharacterMotorMovingPlatform();
 
 class CharacterMotorSliding {
     // Does the character slide on too steep surfaces?
     var enabled : boolean = true;
     
     // How fast does the character slide on steep surfaces?
     var slidingSpeed : float = 15;
     
     // How much can the player control the sliding direction?
     // If the value is 0.5 the player can slide sideways with half the speed of the downwards sliding speed.
     var sidewaysControl : float = 1.0;
     
     // How much can the player influence the sliding speed?
     // If the value is 0.5 the player can speed the sliding up to 150% or slow it down to 50%.
     var speedControl : float = 0.4;
 }
 
 var sliding : CharacterMotorSliding = CharacterMotorSliding();
 
 @System.NonSerialized
 var grounded : boolean = true;
 
 @System.NonSerialized
 var groundNormal : Vector3 = Vector3.zero;
 
 private var lastGroundNormal : Vector3 = Vector3.zero;
 
 private var tr : Transform;
 
 private var controller : CharacterController;
 
 function Awake () {
     controller = GetComponent (CharacterController);
     tr = transform;
 }
 
 function Start(){
 Screen.showCursor = false;
 }
 private function UpdateFunction () {
     // We copy the actual velocity into a temporary variable that we can manipulate.
     var velocity : Vector3 = movement.velocity;
     
     // Update velocity based on input
     velocity = ApplyInputVelocityChange(velocity);
     
     // Apply gravity and jumping force
     velocity = ApplyGravityAndJumping (velocity);
     
     // Moving platform support
     var moveDistance : Vector3 = Vector3.zero;
     if (MoveWithPlatform()) {
         var newGlobalPoint : Vector3 = movingPlatform.activePlatform.TransformPoint(movingPlatform.activeLocalPoint);
         moveDistance = (newGlobalPoint - movingPlatform.activeGlobalPoint);
         if (moveDistance != Vector3.zero)
             controller.Move(moveDistance);
         
         // Support moving platform rotation as well:
         var newGlobalRotation : Quaternion = movingPlatform.activePlatform.rotation * movingPlatform.activeLocalRotation;
         var rotationDiff : Quaternion = newGlobalRotation * Quaternion.Inverse(movingPlatform.activeGlobalRotation);
         
         var yRotation = rotationDiff.eulerAngles.y;
         if (yRotation != 0) {
             // Prevent rotation of the local up vector
             tr.Rotate(0, yRotation, 0);
         }
     }
     
     // Save lastPosition for velocity calculation.
     var lastPosition : Vector3 = tr.position;
     
     // We always want the movement to be framerate independent.  Multiplying by Time.deltaTime does this.
     var currentMovementOffset : Vector3 = velocity * Time.deltaTime;
     
     // Find out how much we need to push towards the ground to avoid loosing grouning
     // when walking down a step or over a sharp change in slope.
     var pushDownOffset : float = Mathf.Max(controller.stepOffset, Vector3(currentMovementOffset.x, 0, currentMovementOffset.z).magnitude);
     if (grounded)
         currentMovementOffset -= pushDownOffset * Vector3.up;
     
     // Reset variables that will be set by collision function
     movingPlatform.hitPlatform = null;
     groundNormal = Vector3.zero;
     
        // Move our character!
     movement.collisionFlags = controller.Move (currentMovementOffset);
     
     movement.lastHitPoint = movement.hitPoint;
     lastGroundNormal = groundNormal;
     
     if (movingPlatform.enabled && movingPlatform.activePlatform != movingPlatform.hitPlatform) {
         if (movingPlatform.hitPlatform != null) {
             movingPlatform.activePlatform = movingPlatform.hitPlatform;
             movingPlatform.lastMatrix = movingPlatform.hitPlatform.localToWorldMatrix;
             movingPlatform.newPlatform = true;
         }
     }
     
     // Calculate the velocity based on the current and previous position.  
     // This means our velocity will only be the amount the character actually moved as a result of collisions.
     var oldHVelocity : Vector3 = new Vector3(velocity.x, 0, velocity.z);
     movement.velocity = (tr.position - lastPosition) / Time.deltaTime;
     var newHVelocity : Vector3 = new Vector3(movement.velocity.x, 0, movement.velocity.z);
     
     // The CharacterController can be moved in unwanted directions when colliding with things.
     // We want to prevent this from influencing the recorded velocity.
     if (oldHVelocity == Vector3.zero) {
         movement.velocity = new Vector3(0, movement.velocity.y, 0);
     }
     else {
         var projectedNewVelocity : float = Vector3.Dot(newHVelocity, oldHVelocity) / oldHVelocity.sqrMagnitude;
         movement.velocity = oldHVelocity * Mathf.Clamp01(projectedNewVelocity) + movement.velocity.y * Vector3.up;
     }
     
     if (movement.velocity.y < velocity.y - 0.001) {
         if (movement.velocity.y < 0) {
             // Something is forcing the CharacterController down faster than it should.
             // Ignore this
             movement.velocity.y = velocity.y;
         }
         else {
             // The upwards movement of the CharacterController has been blocked.
             // This is treated like a ceiling collision - stop further jumping here.
             jumping.holdingJumpButton = false;
         }
     }
     
     // We were grounded but just loosed grounding
     if (grounded && !IsGroundedTest()) {
         grounded = false;
         
         // Apply inertia from platform
         if (movingPlatform.enabled &&
             (movingPlatform.movementTransfer == MovementTransferOnJump.InitTransfer ||
             movingPlatform.movementTransfer == MovementTransferOnJump.PermaTransfer)
         ) {
             movement.frameVelocity = movingPlatform.platformVelocity;
             movement.velocity += movingPlatform.platformVelocity;
         }
         
         SendMessage("OnFall", SendMessageOptions.DontRequireReceiver);
         // We pushed the character down to ensure it would stay on the ground if there was any.
         // But there wasn't so now we cancel the downwards offset to make the fall smoother.
         tr.position += pushDownOffset * Vector3.up;
     }
     // We were not grounded but just landed on something
     else if (!grounded && IsGroundedTest()) {
         grounded = true;
         jumping.jumping = false;
         SubtractNewPlatformVelocity();
         
         SendMessage("OnLand", SendMessageOptions.DontRequireReceiver);
     }
     
     // Moving platforms support
     if (MoveWithPlatform()) {
         // Use the center of the lower half sphere of the capsule as reference point.
         // This works best when the character is standing on moving tilting platforms. 
         movingPlatform.activeGlobalPoint = tr.position + Vector3.up * (controller.center.y - controller.height*0.5 + controller.radius);
         movingPlatform.activeLocalPoint = movingPlatform.activePlatform.InverseTransformPoint(movingPlatform.activeGlobalPoint);
         
         // Support moving platform rotation as well:
         movingPlatform.activeGlobalRotation = tr.rotation;
         movingPlatform.activeLocalRotation = Quaternion.Inverse(movingPlatform.activePlatform.rotation) * movingPlatform.activeGlobalRotation; 
     }
 }
 
 function FixedUpdate () {
     if (movingPlatform.enabled) {
         if (movingPlatform.activePlatform != null) {
             if (!movingPlatform.newPlatform) {
                 var lastVelocity : Vector3 = movingPlatform.platformVelocity;
                 
                 movingPlatform.platformVelocity = (
                     movingPlatform.activePlatform.localToWorldMatrix.MultiplyPoint3x4(movingPlatform.activeLocalPoint)
                     - movingPlatform.lastMatrix.MultiplyPoint3x4(movingPlatform.activeLocalPoint)
                 ) / Time.deltaTime;
             }
             movingPlatform.lastMatrix = movingPlatform.activePlatform.localToWorldMatrix;
             movingPlatform.newPlatform = false;
         }
         else {
             movingPlatform.platformVelocity = Vector3.zero;    
         }
     }
     
     if (useFixedUpdate)
         UpdateFunction();
 }
 
 function Update () {
     if (!useFixedUpdate)
         UpdateFunction();
 }
 
 private function ApplyInputVelocityChange (velocity : Vector3) {    
     if (!canControl)
         inputMoveDirection = Vector3.zero;
     
     // Find desired velocity
     var desiredVelocity : Vector3;
     if (grounded && TooSteep()) {
         // The direction we're sliding in
         desiredVelocity = Vector3(groundNormal.x, 0, groundNormal.z).normalized;
         // Find the input movement direction projected onto the sliding direction
         var projectedMoveDir = Vector3.Project(inputMoveDirection, desiredVelocity);
         // Add the sliding direction, the spped control, and the sideways control vectors
         desiredVelocity = desiredVelocity + projectedMoveDir * sliding.speedControl + (inputMoveDirection - projectedMoveDir) * sliding.sidewaysControl;
         // Multiply with the sliding speed
         desiredVelocity *= sliding.slidingSpeed;
     }
     else
         desiredVelocity = GetDesiredHorizontalVelocity();
     
     if (movingPlatform.enabled && movingPlatform.movementTransfer == MovementTransferOnJump.PermaTransfer) {
         desiredVelocity += movement.frameVelocity;
         desiredVelocity.y = 0;
     }
     
     if (grounded)
         desiredVelocity = AdjustGroundVelocityToNormal(desiredVelocity, groundNormal);
     else
         velocity.y = 0;
     
     // Enforce max velocity change
     var maxVelocityChange : float = GetMaxAcceleration(grounded) * Time.deltaTime;
     var velocityChangeVector : Vector3 = (desiredVelocity - velocity);
     if (velocityChangeVector.sqrMagnitude > maxVelocityChange * maxVelocityChange) {
         velocityChangeVector = velocityChangeVector.normalized * maxVelocityChange;
     }
     // If we're in the air and don't have control, don't apply any velocity change at all.
     // If we're on the ground and don't have control we do apply it - it will correspond to friction.
     if (grounded || canControl)
         velocity += velocityChangeVector;
     
     if (grounded) {
         // When going uphill, the CharacterController will automatically move up by the needed amount.
         // Not moving it upwards manually prevent risk of lifting off from the ground.
         // When going downhill, DO move down manually, as gravity is not enough on steep hills.
         velocity.y = Mathf.Min(velocity.y, 0);
     }
     
     return velocity;
 }
 
 private function ApplyGravityAndJumping (velocity : Vector3) {
     
     if (!inputJump || !canControl) {
         jumping.holdingJumpButton = false;
         jumping.lastButtonDownTime = -100;
     }
     
     if (inputJump && jumping.lastButtonDownTime < 0 && canControl)
         jumping.lastButtonDownTime = Time.time;
     
     if (grounded)
         velocity.y = Mathf.Min(0, velocity.y) - movement.gravity * Time.deltaTime;
     else {
         velocity.y = movement.velocity.y - movement.gravity * Time.deltaTime;
         
         // When jumping up we don't apply gravity for some time when the user is holding the jump button.
         // This gives more control over jump height by pressing the button longer.
         if (jumping.jumping && jumping.holdingJumpButton) {
             // Calculate the duration that the extra jump force should have effect.
             // If we're still less than that duration after the jumping time, apply the force.
             if (Time.time < jumping.lastStartTime + jumping.extraHeight / CalculateJumpVerticalSpeed(jumping.baseHeight)) {
                 // Negate the gravity we just applied, except we push in jumpDir rather than jump upwards.
                 velocity += jumping.jumpDir * movement.gravity * Time.deltaTime;
             }
         }
         
         // Make sure we don't fall any faster than maxFallSpeed. This gives our character a terminal velocity.
         velocity.y = Mathf.Max (velocity.y, -movement.maxFallSpeed);
     }
         
     if (grounded) {
         // Jump only if the jump button was pressed down in the last 0.2 seconds.
         // We use this check instead of checking if it's pressed down right now
         // because players will often try to jump in the exact moment when hitting the ground after a jump
         // and if they hit the button a fraction of a second too soon and no new jump happens as a consequence,
         // it's confusing and it feels like the game is buggy.
         if (jumping.enabled && canControl && (Time.time - jumping.lastButtonDownTime < 0.2)) {
             grounded = false;
             jumping.jumping = true;
             jumping.lastStartTime = Time.time;
             jumping.lastButtonDownTime = -100;
             jumping.holdingJumpButton = true;
             
             // Calculate the jumping direction
             if (TooSteep())
                 jumping.jumpDir = Vector3.Slerp(Vector3.up, groundNormal, jumping.steepPerpAmount);
             else
                 jumping.jumpDir = Vector3.Slerp(Vector3.up, groundNormal, jumping.perpAmount);
             
             // Apply the jumping force to the velocity. Cancel any vertical velocity first.
             velocity.y = 0;
             velocity += jumping.jumpDir * CalculateJumpVerticalSpeed (jumping.baseHeight);
             
             // Apply inertia from platform
             if (movingPlatform.enabled &&
                 (movingPlatform.movementTransfer == MovementTransferOnJump.InitTransfer ||
                 movingPlatform.movementTransfer == MovementTransferOnJump.PermaTransfer)
             ) {
                 movement.frameVelocity = movingPlatform.platformVelocity;
                 velocity += movingPlatform.platformVelocity;
             }
             
             SendMessage("OnJump", SendMessageOptions.DontRequireReceiver);
         }
         else {
             jumping.holdingJumpButton = false;
         }
     }
     
     return velocity;
 }
 
 function OnControllerColliderHit (hit : ControllerColliderHit) {
     if (hit.normal.y > 0 && hit.normal.y > groundNormal.y && hit.moveDirection.y < 0) {
         if ((hit.point - movement.lastHitPoint).sqrMagnitude > 0.001 || lastGroundNormal == Vector3.zero)
             groundNormal = hit.normal;
         else
             groundNormal = lastGroundNormal;
         
         movingPlatform.hitPlatform = hit.collider.transform;
         movement.hitPoint = hit.point;
         movement.frameVelocity = Vector3.zero;
     }
 }
 
 private function SubtractNewPlatformVelocity () {
     // When landing, subtract the velocity of the new ground from the character's velocity
     // since movement in ground is relative to the movement of the ground.
     if (movingPlatform.enabled &&
         (movingPlatform.movementTransfer == MovementTransferOnJump.InitTransfer ||
         movingPlatform.movementTransfer == MovementTransferOnJump.PermaTransfer)
     ) {
         // If we landed on a new platform, we have to wait for two FixedUpdates
         // before we know the velocity of the platform under the character
         if (movingPlatform.newPlatform) {
             var platform : Transform = movingPlatform.activePlatform;
             yield WaitForFixedUpdate();
             yield WaitForFixedUpdate();
             if (grounded && platform == movingPlatform.activePlatform)
                 yield 1;
         }
         movement.velocity -= movingPlatform.platformVelocity;
     }
 }
 
 private function MoveWithPlatform () : boolean {
     return (
         movingPlatform.enabled
         && (grounded || movingPlatform.movementTransfer == MovementTransferOnJump.PermaLocked)
         && movingPlatform.activePlatform != null
     );
 }
 
 private function GetDesiredHorizontalVelocity () {
     // Find desired velocity
     var desiredLocalDirection : Vector3 = tr.InverseTransformDirection(inputMoveDirection);
     var maxSpeed : float = MaxSpeedInDirection(desiredLocalDirection);
     if (grounded) {
         // Modify max speed on slopes based on slope speed multiplier curve
         var movementSlopeAngle = Mathf.Asin(movement.velocity.normalized.y)  * Mathf.Rad2Deg;
         maxSpeed *= movement.slopeSpeedMultiplier.Evaluate(movementSlopeAngle);
     }
     return tr.TransformDirection(desiredLocalDirection * maxSpeed);
 }
 
 private function AdjustGroundVelocityToNormal (hVelocity : Vector3, groundNormal : Vector3) : Vector3 {
     var sideways : Vector3 = Vector3.Cross(Vector3.up, hVelocity);
     return Vector3.Cross(sideways, groundNormal).normalized * hVelocity.magnitude;
 }
 
 private function IsGroundedTest () {
     return (groundNormal.y > 0.01);
 }
 
 function GetMaxAcceleration (grounded : boolean) : float {
     // Maximum acceleration on ground and in air
     if (grounded)
         return movement.maxGroundAcceleration;
     else
         return movement.maxAirAcceleration;
 }
 
 function CalculateJumpVerticalSpeed (targetJumpHeight : float) {
     // From the jump height and gravity we deduce the upwards speed 
     // for the character to reach at the apex.
     return Mathf.Sqrt (2 * targetJumpHeight * movement.gravity);
 }
 
 function IsJumping () {
     return jumping.jumping;
 }
 
 function IsSliding () {
     return (grounded && sliding.enabled && TooSteep());
 }
 
 function IsTouchingCeiling () {
     return (movement.collisionFlags & CollisionFlags.CollidedAbove) != 0;
 }
 
 function IsGrounded () {
     return grounded;
 }
 
 function TooSteep () {
     return (groundNormal.y <= Mathf.Cos(controller.slopeLimit * Mathf.Deg2Rad));
 }
 
 function GetDirection () {
     return inputMoveDirection;
 }
 
 function SetControllable (controllable : boolean) {
     canControl = controllable;
 }
 
 // Project a direction onto elliptical quater segments based on forward, sideways, and backwards speed.
 // The function returns the length of the resulting vector.
 function MaxSpeedInDirection (desiredMovementDirection : Vector3) : float {
     if (desiredMovementDirection == Vector3.zero)
         return 0;
     else {
         var zAxisEllipseMultiplier : float = (desiredMovementDirection.z > 0 ? movement.maxForwardSpeed : movement.maxBackwardsSpeed) / movement.maxSidewaysSpeed;
         var temp : Vector3 = new Vector3(desiredMovementDirection.x, 0, desiredMovementDirection.z / zAxisEllipseMultiplier).normalized;
         var length : float = new Vector3(temp.x, 0, temp.z * zAxisEllipseMultiplier).magnitude * movement.maxSidewaysSpeed;
         return length;
     }
 }
 
 function SetVelocity (velocity : Vector3) {
     grounded = false;
     movement.velocity = velocity;
     movement.frameVelocity = Vector3.zero;
     SendMessage("OnExternalVelocity");
 }
 
 // Require a character controller to be attached to the same game object
 @script RequireComponent (CharacterController)
 @script AddComponentMenu ("Character/Character Motor")