You should check that the point you are going is not outside your map.
I think that when you are adding forces to the rigidbody you can add “too much” forces and that rigidbody collides with something and after that it get stacked.
Edit:
Check the OnCollisionEnter, OnCollisionStay and Exit also the triggers.
http://docs.unity3d.com/ScriptReference/MonoBehaviour.OnCollisionEnter.html
2
solved Player getting stuck on the map