System Locking : Circumstances Point To Firefox (!)^h^h^h^h^h^h^h^h^h Mystery

My system has begun locking up and the circumstantial evidence, much to my surprise, ~~seem to point to Firefox~~. The lockup is a hard one: the screen freezes with no mouse response, no perfmon counters, no hard drive activity. Have to go to the big red switch. I recently re-installed my display drivers (for an ATI All-In-Wonder 800) using the latest Catalyst drivers and normally I would strongly suspect them. ~~But it seems to me that the hangs are at least often and perhaps always occuring right at the moment of switching pages in Firefox. (It just did it as I checked that I was running Firefox

~~Now, opening pages in a browser is a common task, so it's possible that this is pure coincidence. Too, I've had hangs when I wasn't opening pages, but I very well may have had the browser open and experiencing an auto-refresh (such as happens on my homepage, which is Nor does this let my display driver entirely off the hook, as the problem may relate to the display-rendering of a just-changed Web page, right?~~

~~So, after two days of drastic msconfig work, I am ready to try the ultimate sacrifice -- switching to IE. Wish me luck.~~

Update: Well, the good news is that it's not Firefox. Fifteen minutes into a Firefox-less session, I got the freeze. I feel it must be the display drivers, but I don't know what alternatives I have.