UBB.threads PHP Forum Software Community Forums UBB.threads 7 Version 7 Support New members posting not allowed

If you used the cp to login as him then he won't be able to either.

Humm if the Admin log does not list a user I would suspect you may have been hacked.
It would list like:
Date Username User IP Operation Description

So if a user name is missing I would say time for a intrusion cleanup.