Something that can probably stop the spam bots...

[Lith]

phpBB is a huge target for spam bots... I consider reading this:

http://www.phpbb.com/community/viewtopic.php?t=393648
(It's the official phpBB site so no "viruses" or pop ups.

I'm guessing we are using phpBB2 so there isn't a download link for it but I guess it will come soon unless considering to upgrade to phpBB3

And maybe turning on image and email verification will help stop the bots from attacking the forum.

[Ryo-Ohki]

They are already on.