StarDestroyer.Net BBS

My computer semi-randomly crashes. This mainly happens when I'm playing a game like Halo, but it can happen at any time. I'm using a computer with a NF4K8MC-ERS motherboard, a Geforce 6200, and an Athlon-64 3000+. When it crashes, the screen just blanks out for a split second and then I see the bootup screen, and the computer reboots.

Any idea what might be causing these crashes? They're awfully annoying, although mostly an issue while I'm playing games (and therefore not doing anything important).

It sounds like a bad ram stick to me. If it only happened during games I would say "heat problem!" in an instant, but if it happens at other times too, then probably a bad ram stick.