Just FYI, if you're running version 2.2 of the advanced guestbook, changing your admin password won't do a thing. The reason it's so easily hacked is because they don't need your password. The only way to correct that is to upgrade or remove version 2.2.
Ok, sorry Mikej. I thought that advisory thing you wrote was taking care of that. But, otherwise, changing pw often will do no harm atleast?