Anatomy of a hang

[Undertoad]

OK, so does the motherboard monitoring software say anything interesting? It says my CPU is so cool I could touch it, my fans are running fine, and the power supply is producing good voltages -- while the monitor is watching it -- except for maybe a few little hitches on the 12V rail. I write that off to disk usage.

Although I should say, when the system hangs, the disk activity light seems to be at 100%.

Is this problem hardware or software? Of course, it only seems to happen when software is running; the system has remained stable overnight, when it's relatively inactive. So my first thought was that it must be Firefox. The problem started to really get aggravating yesterday, and only appeared in Firefox; Unreal Tournament 2004 worked for an hour, and that'll tax your memory and your whole system harder than Firefox.

But was that just chance?

I disabled smooth scrolling, since it seemed to happen during scrolling. No effect.

I disabled a few extensions that I didn't need, and uninstalled a few that I never used. Often Firefox extensions will make it seem like Firefox itself is unstable. But this had no effect on the problem.