Andrew,
Thanks for the informed response and for explaining that no one who posts
here actually works for Microsoft. I will try what you have suggested, and
thanks for volunteering your time to do Microsoft's tech support for them. In
my experience, answers from the user community are typically better than
dealing directly with tech support directly, as you have less of an incentive
to blame the issue on something else.

I actually followed Peter's advice and posted to the Office community he had
suggested. It came as no surprise when I got the following response:

"It isn't a Word problem and would probably be better answered in a Vista
Newsgroup as it looks like a Vista problem.

However, this problem is normally because there is a dead mapped drive or
other invalid link set in Explorer.

--
Terry Farrell - MS Word MVP"

"It looks like a Vista problem" is precisely what I thought from the very
beginning.

Thanks again.