I updated Spiral Knights today (judging from the forums it was the update to revert the danger missions), and since then I'm unable to log in.
I play through Steam, and when opening SK it'll send me immediately to the knight selection screen (as normal).

When I select my knight, it attempts to send me to the ready room but instead sends me back to the log-in screen with the error "you have been disconnected from the server."

If I press "Logon" again, it'll attempt to log in indefinitely. It doesn't freeze, as everything is responsive; it just won't log in.

I've tried restarting everything: laptop, steam, modem, wireless modem, spiral knights.
I've also tried nixing the game overlay and creating a new knight.
I've also tried deleting local content (through steam and manually), and re-installing.

I'm a bit lost at this point.

Edit: It fixed itself, no idea how or why.
Edit2: Disconnected while playing and now it's back. Man, could this game just decide if it's broken for me or not.
10/8/2013 Edit3(oh my krogmo): It keeps fixing itself and then failing again. It'll work one time, I'll play, log out, try to log in later, and it won't work for a few hours. I give up.