This is the new forum server!
You may need to log out and log back in again. Only a few posts (at worst) should be lost in the transition. Your username & password from before should work, but since we're on a new domain name, any efforts by your browser to memorize your password aren't going to come across.
If you need help, please holler over at the jim-butcher.com feedback form.
http://www.jim-butcher.com/feedback/