On another thread I found someone suggesting it's a problem with Keychain so I am running Keychain access/Keychain first aid... and now IT is not responding. Sigh.
So after force quitting keychain first aid Keychain Access would completely hang on open. So what I did was blow away the entire set of keychain plist files and restart keychain. BINGO, worked just fine (had to reenter a password or two) and now mail preferences opens.