Then I'm afraid either your RAM is bad, or your HDD is corrupt. Chances are that it'd most likely be the RAM. If you have two sticks, run the PC on one of them only and see if there are any BSODs. The one that doesn't give any is the good one, although there are chances both have gone bad. If you want to check for it, download memtest86 (Google for it). It'll download as an ISO, which you can burn on an empty CD and boot your PC with. Let it run overnight on each RAM stick and if you get even 1 error, that RAM stick is bad.