Sorry to bump this thread, but A) I was wondering if you fixed the problem and B) I believe I have a similar problem to you, but I'm not sure whether it is to do with the graphics card I have. The reason I say this is because my computer has just been to the people who built it (www.powerc.com <-very good) and they were running benchmarks and cpu tests etc on it and it didn't crash once the 4 or more days they had it. The one thing I didn't give to them was the Maxtor OneTouch4Plus hard drive that I use to run some of the programs and to back stuff up to. They said it was probably bad sectors on it but I only ran chkdsk a few days ago so maybe it missed something? Also, don't know whether this is related but a couple of days ago my computer would not boot and came up with the message NTLDR could not be found press Ctrl + Alt + Del to restart. It finally booted up once I unplugged the maxtor hard drive. It froze just a second ago and did a blue screen error message which i took a picture of (attached). normally they restart on their own but I had to restart the computer manually. I'm pretty sure its the hard drive but is there any other software apart from chkdsk that can be used to test the hard drive?
