I just ran into this error about 45min ago... still waiting to get back on. Also has happened before maybe only for 15min though but never this long! When I am able to get past the log in screed I get put into a queue, tossed into the game just to be disconnected again by the 90000 error.

Hopefully the upcoming maintenance fixes these issues. Hopefully Square Enix can get their crap together before the big patch. We shall see how this goes! <Holds on ready for a roller coaster ride>