All docs in only one folder are "locked by 'another user'"

We have a user on our network who has all documents in just one of her
folders suddenly opening with "MergeLv1.doc is locked by 'another user'" It
gives options to read-only, notify, or cancel. If you click read-only, you
can open and manipulate the document, but it must be saved under another
name. If you click cancel, it states that it cannot locate the source
document MergeLv1.doc.

These documents have never been mail-merged. The user just enters
information into text form fields, saves changes, and prints.

We attempted to open one document on another PC and it called for the
installation of another piece of Word. Installed MS Office 2000 SR1 and we
were able to open the document normally. However, the user's PC never called
for the installation.

I searched her documents for *.tmp, ~*.do, and ~*.wbk files and found none.
She is using Word 2000 and it has been activated.

We've searched help sites with no luck. Any help would be greatly
appreciated.

Thank you,
Jen