I occasionally get this problem myself, most people say to wait a while before trying again as your account may get auto-banned, however I have found a very weird work around that seems to work for me, although I don't know if it will be successful for anyone else. What I do is I go to one of my accounts that isn't full and I make a new character with some random name then login with that I then switch to one of my other characters on the account and then suddenly everything works fine again and I just delete the new character that I made.
