Need help scripting ladders for a 3d Top-Down level

I think your controller is getting stuck between onCollisionEnter and onCollisionExit. When you jump into the ladder it triggers and allows you to climb but when you reach the top there's probably a couple frames that you exit the ladder collider but then you reactivate your physics and the controller falls back onto the ladder. I can't be sure this is whats happening but I've had this sort of thing happen with a few projects.

The way I would fix this if that is what's going on, is by adding a timer to stop the player from checking to see if it's hit the ladder for a bit so the player has time to move away from the ladder before it checks again.

Something like this maybe.

 void Update()
 {
   if(timer > 0)
   {
     timer -= Time.deltaTime;
   }
 }
 
 void onCollisionEnter()
 {
   //Check for your ladder collider
 
   if(timer <= 0)
   {
     //Turn off your physics and start climbing
   }
 }
 
 void onCollisionExit()
 {
   //Run your code to activate the normal controller
   //then at the end set your timer to some number
   //it doesn't have to be 1 second you can set it lower
   //but I would use at least 1 second to make sure it works

   timer = 1.0f;
 }

Just a personal note, I'm not sure how other feel about this but I'm a bit hesitant to download and open zip files so I haven't actually seen how your game runs. A better option might be to setup a dropbox account and build a webplayer version so you can share it that way.

Ok here is my updated code but it does not even compile. And plus I am doing it in JavaScript, not C# so I'm not sure how your example would translate well to JS.

 #pragma strict
 
 var ChController : Transform;
 var inside : boolean = false;
 var heightFactor : float = 3.2;
 var chMotor: CharacterMotor;
 
 private var FPSInput : FPSInputController;
 
 
 function Start()
 {
     FPSInput = GetComponent(FPSInputController);
       chMotor = GetComponent(CharacterMotor);
 }
 
 function OnTriggerEnter (Col : Collider)
 {
     if((Col.gameObject.tag == "northLadder")||(Col.gameObject.tag == "southLadder")||
     (Col.gameObject.tag == "eastLadder")||(Col.gameObject.tag == "westLadder"))
     {
         if(timer < 0)
         {
         FPSInput.enabled = false;
         inside = !inside;
         ChangeGravity(0.0);
         ChangeAirAccel(0.0);
         }
     }
 }
 
 function OnTriggerExit (Col : Collider)
 {
     if((Col.gameObject.tag == "northLadder")||(Col.gameObject.tag == "southLadder")||
     (Col.gameObject.tag == "eastLadder")||(Col.gameObject.tag == "westLadder"))
     {
         FPSInput.enabled = true;
         inside = !inside;
         ChangeGravity(20.0);
         ChangeAirAccel(15.0);
         timer = 1.0f;
     }
 }
 
 function Update(Col : Collider)
 {
     if(timer > 0)
     {
         timer -= Time.deltaTime;
     }
     if(Col.gameObject.tag == "northLadder")
     {
         if((inside == true && Input.GetKey("w")) || (inside == true && Input.GetKey("up")))
         {
             ChController.transform.position += Vector3.up / heightFactor;
         }
         if((inside == true && Input.GetKey("s")) || (inside == true && Input.GetKey("down")))
         {
             ChController.transform.position += Vector3.down / heightFactor;
         }
     }    
     
     if(Col.gameObject.tag == "southLadder")
     {
         if((inside == true && Input.GetKey("w")) || (inside == true && Input.GetKey("up")))
         {
             ChController.transform.position += Vector3.down / heightFactor;
         }
         if((inside == true && Input.GetKey("s")) || (inside == true && Input.GetKey("down")))
         {
             ChController.transform.position += Vector3.up / heightFactor;
         }
     }    
         
     if(Col.gameObject.tag == "westLadder")
     {
         if((inside == true && Input.GetKey("a")) || (inside == true && Input.GetKey("left")))
         {
             ChController.transform.position += Vector3.up / heightFactor;
         }
         if((inside == true && Input.GetKey("d")) || (inside == true && Input.GetKey("right")))
         {
             ChController.transform.position += Vector3.down / heightFactor;
         }
     }
     
     if(Col.gameObject.tag == "eastLadder")
     {
         if((inside == true && Input.GetKey("a")) || (inside == true && Input.GetKey("left")))
         {
             ChController.transform.position += Vector3.down / heightFactor;
         }
         if((inside == true && Input.GetKey("d")) || (inside == true && Input.GetKey("right")))
         {
             ChController.transform.position += Vector3.up / heightFactor;
         }
     }
 }
 
 function ChangeGravity(g: float){
   chMotor.movement.gravity = g;
   chMotor.movement.maxFallSpeed = g;
 }
 
 function ChangeAirAccel(a: float){
 
     chMotor.movement.maxAirAcceleration = a;
     
 }

And by the way I have a dropbox account but I do not know how to make a webplayer version and share it. Is there anyone else who may want to look at my file?