Are these all on Radeon cards ?? I had the same problem a while ago on different things where it either :
A - Went to full reboot
B - Screen went black, sound kept going, then eventually looped
C - Went to BSOD with some divide by zero error
I think it was a mix between my graphics card and dodgy memory, but in the end, I swapped it for a GForce card, and no more probs. Not much help to you, I know, but maybe try different things like dropping down to 4x AGP, turning off fancy settings etc ?
Jesus loves you. Everyone else thinks you're a cun........