Another case of a lost day and some failure of Google. Here's what went down (going back a bit):

1. A few weeks ago I installed the latest Vista service pack. The installation apparently reset my preferences for automatic updates. I always choose 'Download updates and notify me' rather than the 'automatic install' option. But, SP2 reverted it to the auto. install option, with the time set for 3am.
2. Vista wakes my laptop from sleep in the middle of the night, installs updates that require reboot. The nag comes up, counts down, then force quits all of my open programs, notably MS Word, and reboots the computer.
3. I wake up to find that my copy of Word is completely and totally shazonked. There are a variety of bizarre symptoms. It starts, then hangs. It starts, doesn't crash, but I can't move the mouse. It starts, lets me access the options menu, but crashes when I try to change anything. You name it, I saw it.

Here's the failure of Google. What do I search for? At first, I think it's about the EndNote add-in. I remove it, no dice. I try to repair the install. I try to repair the install from the original DVD. Nothing. I'm trying to disable all the templates and add-ins, but it crashes when I try to change anything. And here's the kicker… you can start Word from the command line with the '/a' operator to load it without any templates and add-ins if you think one is corrupted and causing a problem. But when you do that, it's not like booting in safe mode where you can view and change the normal configuration. You go look at the options and find out that no add-ins or templates are there. Argh!

Anyway, enough back story. To the solution: create a system restore point, and then delete the registry key at HKEY_CURRENT_USER\Software\Microsoft\Office\version number\Word\Data. Word will regenerate it automatically the next time you start it. Apparently, force quitting can cause the data stored in that key to be corrupted and cause all manner of crazy problems. Sheesh.