<sigh> It can never be the obvious, easy answer, can it? (Or if it is, one
doesn't ask the question, so it goes round in circles because of that.)

FWIW, the only time I've ever seen anything even resembling what you report
is when  user has opened a file directly from, say, an Outlook email message.
They'll work, save assiduously, close... and all the changes are lost,
because the file they were saving to was a TEMP file that was destroyed when
the document was closed. (This, from personal experience living in a
household with someone who's a durn good beta tester - can break anything
without even trying.)

Other than that, there's been the occasional "murmer" here in the NGs where
users have complained on occasion that this is happening. Unfortunately, I
can't recall the Windows+Word combination where that was happening (if those
people ever did respond and tell us). But those reports were very few, and
very far between...

If you're seeing this consistently, though, then I have to suspect something
in how your application is working with Word, or a system configuration
problem. Some kind of "management" software or anti-virus software, for
example, that might be interfering with the file management. Is there
anything of this nature installed? If you boot a system where this is
happening all the time in Safe Mode, does it still occur?

 -- Cindy