Are you having overheating issues on your cpu or vid card, CD? The heavy rendering and opengl progs could do that.... and overheating tends to create random reboots (in my experience).

Not so long ago, my old internet pc was doing the random reboot and freeze thing until I shovelled some dust out of its cpu heat sink and fan. Runs reliably now.... most of the time... so it looks like it was an overheating issue (as caused by the dust restricting heat/air flow off the thing).

Dreams are just nightmares on prozac...
Digital WasteLanD