Codecs for wmp have not been released with W8.1 which breaks the game.
http://forum.square-enix.com/ffxiv/threads/107619-Game-not-logging-into-character-select-screen?p=1436790&viewfull=1#post1436790
Glad I saw this at work, otherwise I probably would have.
Edited title
Edited, Oct 17th 2013 7:54am by SolomonGrundy