I think I may have figured this out. If I have, I feel REALLY, REALLY dumb.
The dbs are on a server, and we started using Tony's Auto FE Updater about
three months ago. The permissions are set by group, not user. I haven't had
an .mdw file on my development area, so I've been resetting the permissions
on the server with the icon that starts the Auto FE Updater. That means that
I've been setting the permissions on the FE copy on the workstation in the
user's profile. I just linked an .mdw to my development FE, changed
permissions, and then copied that FE in a test environment. I'll put the FE
with the correct permissions on one of the real sites, but I'm pretty sure
that's the problem. It really explains why I could "fix" the permissions on
a user's profile and they would stay "fixed" until I deleted the user's
profile. DUUHHH! I've always set permissions directly on the server, but
everyone was pointing to the save FE until we implemented the Auto FE
Updater. Thank you, Rick and Joan, for responding to this issue over which
I've lost a lot of sleep. If there are flaws in my current perception,
please let me know. I think I've lost about any confidence I had.