Unity Crashing back on desktop

Ok I am having some problems with Unity, when I try to test my game it keeps quiting and going back onto desktop, its a racing game and at the moment I just have one track one ship with a terrain, and thats about it.

The island demo that comes with unity works and it has far more deatail then my game, so I dont understand it :S.

Any help would be great.

Disable components one by one until you find the culprit causing the crash.