
I had this occur just before you posted, probly around the same time so it's not likely an error on your end.
It happened while I was swapping characters to craft several times so that may have something to do with it.
Sometimes I get errors that say my acc is already logged in. If a Client doesn't fully shut down there my be something running you could shut down with Task Manager or just to a Full CP reboot.
I also wonder if accounts are set at different priority levels based on how long you've been logged in or how often you swap characters if they boot people to make room for someone else. Or maybe the servers can't handle the number of incoming logins at once. idk