Could mean a server change.  This happens for 15 minutes as they update the server to the new version.  Just a guess.  Fingers crossed that is the reason, if not, then wait and try again.

Come to me once today. Before that the interface was very very slow, like freezing and taking 30 sec until anything happened when I push a button. I decided to quit and when I later tried to log in it gave me the invalid pass thing. But it worked again later. So they probably did something at that time.