Digital signature
 

I have a shared workbook to which I have added a digital certificate (created
by our worksite administrator). The digital certificate is periodically
discarded even though no changes are made to any of the exisiting VBA code
associated with this workbook. I can't find a pattern to why or when it is
discarded; sometimes the message appears while the file is sitting open and
idle on the desktop! I have the workbook set up as shared to take advantage
of the history report that can be generated to track changes. Is there
something incompatible between a digital certificate and a shared workbook
for this purpose?