Well, I can follow the link succesfully, so you clearly must be an inferior Avtoritet. Perhaps I should revoke your priveleges completely for trying to break the forum! Invalid session, eh? I'll show you an invalid session!
In case you were actually wondering what it did,it just lists all the threads, and puts tick boxes nest to them so you can quickly lock/unlock, etc. large groups of threads.
I can reset you if you need to be, but the session error is more likely because you came in through a shortcut and it didn't have a valid session. You can try logging out and then back in to re-establish a new session.