OS X Leopard 10.5: The unknown user and group bugs

I waited quite a while before upgrading to Leopard (OS 10.5). I knew the OS had had a turbulent childhood, so I waited for 10.5.3. Even so, I've run into two ugly and common bugs and one weird and exotic one:

• Upgrading to OS X 10.5.1: LaunchDaemons
• Permissions - apps cannot be updated
• Keychain First Aid 10.2 running on OS X 10.5

Now I'm on common bug #3. After upgrading from 10.4 (Tiger) to 10.5 (Leopard) an "unknown user" and/or "unknown group" appears in every user account when viewing sharing and permissions. It will also appear in the file sharing preference panel. It can be removed from the preference panel, but there's no proven safe method to remove this "user" from the OS. I've reviewed a number of web postings on this and related topics:

• discussions.apple.com/thread.jspa?messageID=8028824 - cosmetic issue?
• the "unknown group" bug
• Mac OS X Hints discussions
• here and here
• Apple kb article from Dec 2007: a very unsatisfactory terminal fix
• Apple - Support - Discussions - Leopard Permissions Unknown and ...
• macosxhints.com - 10.5: Manage users and groups using a GUI tool (this is an interesting reference, but in fact you can add users and groups in 10.5 directly in the accounts pane)

After reviewing all the references, and the wars about which unix comands might help, I have these tentative conclusions:

• this was a very bad bug prior to 10.5.2, but after 10.5.2 it's supposedly a cosmetic problem
• Apple made big changes to how permissions work in 10.5 (but "repair permissions still finds "problems" right after an OS X archive and install, so they have work yet to do somewhere), that led to this problem.
• Anyone who used Netinfo to create shares or used SharePoints in 10.4 or earlier might have extra problems.

I'm going to leave this bug alone and see if 10.5.5 does some clean up. In addition to being an annoying blemish it is the sort of defect that comes back to bit us in combination with another bug or future update. There's a rumor that after a year or so repeated train wrecks (MacBook Air, 10.5, iPhone 2.0, MobileMe) Apple may decide to focus on quality. So maybe they'll get around to cleaning up this icky one.


Update 3/11/2010: Apple never did clean up 10.5. By the time I migrated the 10.5 accounts to a 10.6 machine the permissions were a mess. I think Apple shafted us with this particular bug. In 10.6 one can delete the unknown user.