unity crashing every 5-10 minutes

unity start normaly but right after a couple of minutes it freezes and crashes for no reason, i imported a model for maya unto unity using the .fbx file extension could that be problem or unity just doesnt like vista? or could it be my computer isnt powerful enough?

Review the crash logs in Help > Report A Bug to see if it was something you did or not. You can also send this information to the Unity development team, and they'll try and help you fix it. Unfortunately we can't just give you an answer here... there are lots of reasons that Unity crashes, and without more information we really can't help you.