I have the same issue, so I open a bug :
Bug 59500 – Error when deleting an account when account in maintenance mode.
But after a few testing, here are the result :
- No error in CLI.
- An error occurs only when deleting an account with admin interface with Firefox 4 (Windows XP) and then there is also an error in CLI.
- No error with Firefox 3.6.16 (Windwos XP).
With the accounts in error, my only solution is to kill them with an ldap client.