Is there a way to Determine if an MDB has been opened twice, or if a given
code process is currently running? I have a client who makes multiple copies
of the .mdb and occasionally opens more than one, and each has full copies of
code and linked tables, and there is a process that should NOT be run
concurrently.

I've suggested storing a flag in one of the linked tables, but that is not
the client's preferred approach .. they would prefer something like VBs
"App.PreviousInstance", but not on the whole .mdb, just on the code (sub)
that's running. I don't think this is possible, but thought I'd check first.