In the way of computers and their miserable antics, my attempts to figure out my system freeze led to a disaster. After determining that my system continued to freeze even when using the "VgaSave" graphics adapter, I began to suspect that it might be my Wireless Network Card (a WMP54GX). I hadn't updated the driver but freezes definitely seemed more common while accessing the Web (causing my initial misguided suspicion of Firefox) and background behavior could additionally trigger network access for the other, seemingly random freezes.
So, using Device Manager I disabled my network card. I rebooted and the system had lost my identity. That is, somehow, c:\documents and settings\larry was not-quite-deleted, but I think all of its sub-directories were. All of my start programs, desktop, settings, etc. were gone. Further, so too were directories gone from the 'all users' account. And there was something weird about the registry -- when I tried to switch "View options" in Explorer (so I could see hidden files and show extensions and all that sort of stuff), it "wouldn't take." As if data wasn't being properly written into the Registry under CURRENT_USER.
So that kind of sucked and I played around for a bit before deciding that the system was so screwed up that I had to take the ultimate risk -- restoring from backups. I have Acronis TrueImage on a daily backup to an internal drive. I pointed at the OS partition (I have partitions on various drives for OS, bin (Program files), data, media, and a non-backed-up "volatile" partition) and chose a restore point of last Thursday, before the freezes started. Acronis rebooted into itself and a few hours later told me it was finished.
I think this is the first time in my life that an emergency restore worked perfectly: the very stuff that I had lost came back and because I keep my data on another partition, I didn't even lose any email. I may have lost some files I'd temporarily stored on the Desktop, but otherwise, I feel like the luckiest guy on Earth. Now all I have to fear is my deep suspicion that the problem was caused by some auto-update facility.
So... Acronis TrueImage 8 (I think they're up to 9 or even 10 now) on a daily backup to an internal SATA drive. (N.B.: If I'd relied only on RAID, I'm fairly sure I would have been screwed.)
OK, back to posting about software development issues, I promise...