Somewhere in your
"C:\Program Files\Macromedia\Dreamweaver MX 2004\Configuration"
folder some files got fucked. i ran into the same problem a while ago. theres 2 solutions, if you have the actual program (meaning you really own a copy) you can reinstall without overwriting your settings (ftp logins, preferences)
now if youre like 90% of all dreamweaver "owners" out there, you ... may have misplaced your CD

in that case, like my friend here above me, bite the bullet and do a full reinstall.