So I can't post an image of this problem but the message I get from trying to log in is....FORBIDDEN : invalid account token. Why?
Hi, Marigolde! Do you use the "Remain Logged In For 8 Hours" option? If so, that is likely the cause of your problem. While it is a bit of a convenience, I recommend you turn that off as it often results in login issues right after a server restart or a patch. You might need to go into your UserPreferences.ini file and remove your login information there, it will look like a big paragraph of random characters.
This is just a guess, there could be some other issue. Try what I suggested and report back if it doesn't work.