Thanks John,

That works like a charm in XL 2003. It would be a treat if I can also
stop XL 2007 users from sharing the workbook. I thought of capturing
the user clicking on the share workbook option in the
Workbook_BeforeSave procedure with something like:

With ThisWorkbook
If .MultiUserEditing Then
<code that cancels sharing
End If
End With

But this only triggers once the workbook is already saved. Has anyone
else tried to prevent w/b sharing in XL 2007? Or what do other people
do with users that try to share a w/b that will lead to errors if
shared?

Les