My account vanished; I tried to log in, and it told me my email address no longer existed. The login failed in both IE and Mozilla.
I created a new account, so it is no big deal, but it is a bit annoying losing my favorite threads information. Plus, it might be an indication of a more serious problem.
My new account has the same email address as the old once, so assuming that email is a unique field in your database tables, my old account must really be missing.