A funny thing happened after I installed Windows Vista Service Pack 1 on my PC: Word 2007 started crashing whenever I closed it, and all but a handful of the application's settings became inaccessible.
I still haven't figured out how to keep Word from crashing on exit, but I regained access to the program's settings by disabling all add-ins. Unfortunately, it took me the better part of an afternoon to figure out this partial solution, and I'm no closer to finding the source of the crashes, though Vista SP1 is the prime suspect.
My first attempt at a fix was to close Word, and then find and rename the Normal.dotm template (it's called Normal.dot in earlier versions). Word simply recreates the template the next time it opens, with all settings back to their defaults. This catch-all repair, which I've used in the past to reset Word, had no effect this time. I then decided to run the Microsoft Office Diagnostics utility. Since I couldn't access the program via the Resources tab in the Word Options dialog box (only the options on the Popular tab were available), I ran it from the Start menu shortcut under Microsoft Office Tools.
None of the tests indicated any problems, though one of the results directed me to check "Download a file periodically that helps determine system problems" in the Privacy Options dialog box, after which I was instructed to wait a week for the problem to fix itself.
I reopened Word without loading the Normal.dotm template or any add-ins by pressing the Windows key, typing winword.exe /a, and pressing Enter. This allowed me to get to all the Word options, and to close the program without crashing. That told me the problem had to be due to a Word add-in. (The privacy setting the diagnostic program referenced was already checked, so that advice turned out to be pointless.)
I clicked the Trust Center tab in the left pane of the Word Options window, then the Trust Center Settings button, and the Add-ins tab on the left. There I checked Disable all Application Add-ins (may impair functionality) in the right window. Since my "functionality" was already pretty compromised, I figured I didn't have much to lose.
When I reopened Word the normal way I could access all settings, but the program still crashes whenever I close it. I searched the error code and mso.dll it mentioned and tried several of the suggestions offered in various forums, but nothing solved the glitch: Not updating my printer driver, not editing the Registry, not even relocating my Office 2007 installation. I may have to use System Restore or my most recent image backup to reset my PC to its state before SP1 was installed, but I'm going to wait a while before taking this step in hopes that a patch becomes available, or I stumble upon a fix.
Tomorrow: the pros and cons of Windows' System Restore.