Seems it is a common problem. Some say the solution is to go on the Web app and create a new squad. Only problem with that is you can't get on the web app at the moment. Sucks because this is the main reason I bought FIFA!
I managed to get back on this morning by doing the Web app fix (creating a new empty squad in the squad list), but an hour ago it locked me out again :( no UT for me tonight! Hope they fix it soon, this is all I really play on FIFA!