It seems that this problem is attributed to the current version of phpBB. Apparently somehow there's a vulnerability which allows spam bots to bypass the e-mail registration and begin posting. Other forums are also having this issue, and phpBB is aware of the problem and I believe that they're working on it.
In the mean time, I know it's annoying, but there's not a whole lot we can do about it (besides changing the registration type to admin, inwhich case I'd have to approve every single person who joins here, and that would be *such* a pain in the eye.)
It would be nice if everyone would try to ignore the bots. When they post, instead of making a reply, either ignore it, or notify a mod. One way or another someone will take care of it, but there's no point in paying any attention to their useless ramblings, wouldn't you say? (Unless, of course, you are indeed interested in purchasing Viagra... inwhich case, I would ask that you do that via other means, please, and without telling us, because I don't think anyone wants to know.

Thanks so much for your patience and cooperation. I know it sucks, but we just gotta deal with it I'm afraid.
Erynn