I have myself set to login automatically everytime I visit, but when I visited just now, it kept giving me "Sorry, you have provided an invalid password." I logged out, but the logout didn't succeed (I even forced a refresh to make sure it wasn't cached). I had to go clear my cookies. At that point, I forced a refresh to make sure it wouldn't return a cached page, and it still gave me the same crap, except it stated that I was logged out. I went to the login page, entered all of my login information, and clicked login after that, at which point I successfully logged in and was able to view pages with no problem.

Sounds like a cookie issue, not a forum bug; when theres an issue with cookies (such as a cookie cleaner cleaning out soem [censored]) it'll fail, as your login depends on your cookies.