It could be anything. In order to work out what it is we need more info. What is your Operating system XP? or ME or 98 what speed is your PC how much memory do you have and when does it crash? Is it when you first switch on or after its been on for a while? Is there something you do just prior to it crashing or is it totally random? Have you installed any hardware or software recently that could be causing it? More info please.