If chat "messes up" and believes you're in a room when you're not, the best bet is to logout using the logout button in chat, and then wait about 2-3 minutes before trying to enter again (restarting your browser just to be safe).

The server should notice you're not connected and disconnect you after that time period has passed. Then you should be good to go to log back in.

If you try logging out and logging right back in, that probably won't work. We'll work to see if we can't get this issue fixed. Trying a different browser might be worth it as well...