Security problem

My guestbook is hack for a couple of times. I can chance username password from the admin but don't help. Password survernam chance doesn't work. What is here the problem
and how can I remove the problem???

Thanks in advance!
Arie

I'm assuming you are using Advanced Guestbook 2.2. A search of these forums using the search feature would provide you with multiple threads on the matter of this guestbooks vulnerability and the fix for it.