Some TPU users are reporting CD key errors when they try to join TPU when there's an expansion map running (Road to Rome or Secret Weapons).
I just cleared the CD key ergc values from the server and restarted it, so hopefully those issues are now resolved. Please let me know if you find otherwise.
Sorry for any inconvenience!
UPDATE 2009Oct10: Apparently the issue still exists for some players, with Mimoyecques in particular triggering the error. I'm working on it...