This has just started. I have two accounts, and whenever I try to login it says "Name or password is invalid", even though I am 100% sure my password is correct. Guest works fine, but all usernames do not.
Uh, yes, something's very wrong, even my account doesn't work. Hm  ???
Probably database server crashed, I'll have a look...
So, it works again.
For some unknows reason connection to database failed.
I use mySql database server, with java-mysql-connector. I heard some rumours that it has bugs, but I was not taking it seriously. Hm. I'll search the web