That's right. Registration works again. I'm reinstalling the rest of the mods as we speak, so the forum should be back to normal (well aside from the lost posts) soon.
Apparently there is a nice big gaping security hole in phpbb. So because some little kid that saw hackers too much and knows how to read got bored, he destroyed our database. We've got user info saved, but he destroyed all our posts and forums. Fun.