2010/01/08: YOU'LL NEVER GUESS WHAT HAPPENED THIS TIME!
Okay, it wasn't my fault this time! Well ... okay, it was, but it wasn't due to perennial stupidity on my part.
So, I forced a shutdown while my computer was shutting down, and this morning, when I tried to login to Windows, the keyboard wasn't working. So, I decided to run a "repair Windows" thing, in preparation for logging in, backing up stuff, and reformatting. That didn't work because typing on a keyboard still wasn't working ... and now I couldn't finish logging in either way because it kept wanting to continue the installation. Then I got the brillaint idea of trying to install Windows on an external hard drive instead. That didn't work because it BSOD'd shortly after trying, and then no matter what I did, it gave a "could not load Windows because Windows\System32\hal.dll is corrupted or missing."
So then I got our computer guru to let me borrow a hard drive and a docking station so that I could install Windows on the borrowed hard drive so I could back stuff up in preparation for an actual reformat ...
... and then I realized that the one thing I failed to back up was my Firefox install. Meaning, I'm going to have to get cookies and install recent addons all over again, whee!
(Oh well, I saved everything important, and it's better than losing EVERYTHING.)