[tobybird]

I, too, own a similar type board so girl, I know the d-r-a-m-a.

If you're not already aware, you have the ability to view member's registration and post IP addresses here: AdminCP - Users - Search IP Addresses. Are you sure that hack isn't pulling the members registration IP?

As far as registrations, what about approving them manually for a bit? At least you'd be able to check out the IP first. I'd keep in mind, though, trying to limit membership based off a local MD IP may cause you to lose legitimate members. What if a member is using a wireless broadband service to access the web or is behind a firewall at work.