Guestbook was hacked.

Apparently someone has hacked my guestbook? Or something. The main page now is white, with only the small drop down menu left that only has the guestbook link in it, and it says root system something or another and "Fuck USA" below that. I also can no longer log in to my administration area....Um, help? Possibly?

A link to it would be helpfull.

If you are running version 2.2 then you probably have been "hacked". If this is the case you need to delete the hacked entry and apply the exploit fix which I have posted elsewhere in these forums. The other thing could be that you have allowed HTML and they have used that to deface your site. The guestbook allows ALL HTML if you tell it to accept it.