Comment 21 for bug 431147

Interesting note:

As a test, I created another non-admin account on the machine with this problem. I rebooted and logged in as that user. As that user, both gdmsetup and admin-users work correctly. When I click the "Unlock" button I am prompted to authenticate. This problem seems to be only related to my other "admin" account. This appears to confirm that it's an account-specific problem... but I have no idea what to check on that account to make it work correctly.