I got a call from a lab manager that's had a large number of clients
that are resetting the first network drive back to F from M. The
problem is that the workstations are locked down and users of the
workstations aren't able to use thumb drives as a result of the change.

I haven't been able to locate any TIDs about this. I'm certain that
users aren't resetting this because they don't have access. Is there a
way to lock this setting permanently?