Not sure if this is the answer, but is there any kind of VBA autosave tool
installed on the machines you are having trouble with. Saving a vba project
on a machine that does not hold the original of the certificate could cause
the certificate to be discarded.

Robin Hammond
www.enhanceddatasystems.com

"G. Drager" wrote in message
...
I have several spreadsheets with Macros that I deploy throughout our
school district with security level locked at high. I sign all the macros
for any spreadsheet and have deployed the trust to all computers (done at
HKLM level, so users cannot alter the trusts). By in large this works
well.
However, I have some users that, through no fault of their own, manage
to
somehow strip the signatures from their document. All macros are password
protected, so they can't alterany code. I can open the document from a
development machine, apply the signature, and then visit their classroom
and
work with them without any problem. The next morning, I will get a call
that
they were working on it again and the macros are broken again (the
signature
is MIA again).
I'm at a loss to explain what they may be doing to cause the signature to
be removed...I can only imagine that something is causing the code to
change
and invalidate the signature even though they really can't access it.
So is there any method to further protect the code/certificate to make
sure things don't get changed?