[Clockworkers Doll]

Sorry to pop into this thread only a few mere hours after it's posted, but friend's having the same issue and it saves me from making my own thread. That fix for skins does not work, as my friend said everything was as it should be when he checked the file.
It is indeed triggered by trying to play Yenten, though. The game does black screen you and when you relog, you get stuck at the title screen. Your alts are fine (IE: If I logged into Clockworker's Doll and got the Yenten bug, I wouldn't be effected on Elluka Clockworker) however, and it only blocks the key you were activated it on.
Getting booted also doesn't fix it.
This is obviously a huge issue, since it can practically break the game for people who try to play at any of the Yenten tables.

EDIT: After looking at that thread again... I don't see how you thought this was a skin issue, Miv. This is a thing with the game/Yenten itself. But I guess it's because OP didn't exactly have a lot of info on it.

EDIT NUMBAH 2: Wait till the next reboot. Then you might be able to log back in.