I have a new machine, using ASRock N68-S MB and AMD 7750 CPU, which is crashing fairly regularly. Symptoms: The display fills up with random, repeating patterns, and the machine is dead - can't get to it from other machines on the internal network.

I thought it might be a memory problem, but swapping out memory didn't change things, and memtest running overnight didn't report any problems.

CPU temp. (according to bios) is never over 40C. There's nothing in any of the logs that indicates any problems - when it hangs, it's dead.

MB has on-board nVidia GeForce 7025/nForce 630a chipset, and I'm using the ver. 180 driver with compiz enabled & running fine.

Any ideas on how to debug this, or at least find the cause? Should I try an older version of the driver? Anyone seen a similar issues?