Like on my Slick Adventure Game, sometime he will stop moving.
http://flowlab.io/game/play/38217
Post a link to your game, and then explain how to reproduce the problem, and it will be much easier to help you out.
It happens with resized players 
I ran through the map to the end, back to start, and to the end again with no problems.
To me, the opposite happened. I keep going no matter what.