It only does it in BF2. But BF2 is the only game I have that will work my system. The only other game I play is Medal of Honor, and I get 350+ FPS in that on max settings...so that's not intense at all.
I had no problems with Prime 95, but that doesn't test your video card.. so I can't be sure.
It maybe the new 1.22 patch for BF2 just doesn't want to work properly with my video card though, who knows. Other people I play with get occasional CTD's, but they don't get total system lock-up like I do.
It will take a few days to determine if the problem has gone away from the changes I have made. Sometimes I can play for a week straight with no problems, other times I get 3 - 4 lock-ups in a half hour. But I will post results when I get them.
I also thought I would be seeing artifacts before it would lock-up, but who knows.