Character turns invisable on build

So I recently got unity 5 and started on a new game. When the i finished the prototype I decided to make a buld and play test it. On my computer it runs fine but when I load it on another pc the character becomes pink for a second then disapears (Not destroyed just invisable). I have no idea how to fix this problem if anyone has come arcoss this please help me I'm getting really annoyed of it.