Am i understanding right your pc is crashing sort of randomly? Sometime's it goes for hours and sometimes it only takes 5 mins, but always when you are doing something intensive on it, never when just using windows/word/internet explorer or things like that? Have you checked that your memory is not broken? I had the same problem when i build my current pc, i had to return most parts to the store, they sent everything back but i got new ram and since then it doens't occur anymore.Hope you can solve your problem,Wouter