Character Controller strange collision bug

I've been testing until now and as far as I can see the problem is FaceMovementDirection() that is causing this.

I simplified my script for faster approach:

 #pragma strict
 
 // This script must be attached to a GameObject that has a CharacterController
 @script RequireComponent( CharacterController )
 
 var moveJoystick : EasyMobileJoystick;
 var rotateJoystick : EasyMobileJoystick;
 
 var cameraPivot : Transform;                        // The transform used for camera rotation
 var cameraTransform : Transform;                    // The actual transform of the camera
 
 var speed : float = 5;                                // Ground speed
 var jumpSpeed : float = 8;
 var inAirMultiplier : float = 0.25;                 // Limiter for ground speed while jumping
 var rotationSpeed : Vector2 = Vector2( 50, 25 );    // Camera rotation speed for each axis
 
 private var thisTransform : Transform;
 private var character : CharacterController;
 private var velocity : Vector3;                        // Used for continuing momentum while in air
 private var canJump = true;
 
 function Start()
 {
     // Cache component lookup at startup instead of doing this every frame    
     thisTransform = GetComponent( Transform );
     character = GetComponent( CharacterController );    
     
     // Move the character to the correct start position in the level, if one exists
     var spawn = GameObject.Find( "PlayerSpawn" );
     if ( spawn )
         thisTransform.position = spawn.transform.position;    
 }
 
 function FaceMovementDirection()
 {    
     var horizontalVelocity : Vector3 = character.velocity;
     horizontalVelocity.y = 0; // Ignore vertical movement
     
     // If moving significantly in a new direction, point that character in that direction
     if ( horizontalVelocity.magnitude > 0.1 )
         thisTransform.forward = horizontalVelocity.normalized;
 }
 
 function OnEndGame()
 {
     // Disable joystick when the game ends    
     moveJoystick.Disable();
     rotateJoystick.Disable();
     
     // Don't allow any more control changes when the game ends
     this.enabled = false;
 }
 
 function Update()
 {
     var movement = cameraTransform.TransformDirection( Vector3( moveJoystick.position.x, 0, moveJoystick.position.y ) );
     // We only want the camera-space horizontal direction
     movement.y = 0;
     movement.Normalize(); // Adjust magnitude after ignoring vertical movement
     
     // Let's use the largest component of the joystick position for the speed.
     var absJoyPos = Vector2( Mathf.Abs( moveJoystick.position.x ), Mathf.Abs( moveJoystick.position.y ) );
     movement *= speed * ( ( absJoyPos.x > absJoyPos.y ) ? absJoyPos.x : absJoyPos.y );
     
     // Check for jump
     if ( character.isGrounded )
     {
     
     }
     else
     {            
         // Apply gravity to our velocity to diminish it over time
         velocity.y += Physics.gravity.y * Time.deltaTime;
         
         // Adjust additional movement while in-air
         movement.x *= inAirMultiplier;
         movement.z *= inAirMultiplier;
     }
     
     movement += velocity;
     movement += Physics.gravity;
     movement *= Time.deltaTime;
     
     // Actually move the character
     character.Move( movement );
     
     if ( character.isGrounded )
         // Remove any persistent velocity after landing
         velocity = Vector3.zero;
     
     // Face the character to match with where she is moving
     FaceMovementDirection();    
     
     // Scale joystick input with rotation speed
     var camRotation = rotateJoystick.position;
     camRotation.x *= rotationSpeed.x;
     camRotation.y *= rotationSpeed.y;
     camRotation *= Time.deltaTime;
     
     // Rotate around the character horizontally in world, but use local space
     // for vertical rotation
     cameraPivot.Rotate( 0, camRotation.x, 0, Space.World );
     cameraPivot.Rotate( camRotation.y, 0, 0 );
 }