1) If you try and register a username that you previously "FaceBook Connected" with it will say the username is not available.

2) After "FaceBook Connecting", it seems like you are registered. However no password is sent to your email, yet the board allows you to Edit Profile. Tried to use Change Password Dialog but since I did not know existing password that didn't work either.

Just a suggestion, fix the FB Connect feature or just remove it entirely.