Well the title says it
I have this guestbook on my website where people can write a little greeting, but lately it has been spammed up with useless stuff and links. Yesterday I re-uploaded the database so that over 80 spam messages were deleted, but they are baaack
I am quite sure that it's a bot of some kind and not a human that spams it.
I have never had such a problem before, so my question is:
Can I change my code or the database inorder to get rid of the spam?
Link to guestbook (my site is in Danish):
http://www.x2zen.dk/gb.asp
/ 
