When I get badnavs(Quite often) I can't get out. However, recently I found a workaround for it that always manages to work.
When you time out, DO NOT go to the main page and log in(or refresh for that matter. It should look as if you're in the game.), but log in with the mailbox window.(If you don't have one open, I don't know what to tell you.). You should get the Badnavs screen. Now, exit that mailbox, and through the main page, open a new mailbox. The MB should come up no problem. Now, through the main page, go to another location, and you should be good.