I continue to get user registrations with registration turned off.

I'm trying to figure out how new users are signing up. I have registration disabled in the network admin, and "add new users" unchecked in network admin. I've deleted all accounts except for 7 subscriber level accounts that I control... but there are still user registrations occurring. It was suggested to me that buddypress may be the culprit, even though the signup page disappears when I disable registration in the network admin. I'm using the blogs mu theme, wordpress multisite and buddypress all up-to-date. Any ideas?