Banned on registration

[Scr00L00s3]

What would cause lifetime banning upon new user registration? The forum was set for email verification and image verification a week ago to try and stop spam posting. Now any user awaiting email conformation receives a lifetime ban.

When I goto ACP and view banned members there is a list of lifetime bans but they have not been banned by a staff member. It appeas they have banned themselves ???

eg:

user: example_user
banned by: example_user
banned on: 3/23/07
ban period: permanent
ban will be lifted: never
ban time remaining: forever

I have reverted the settings back to no image or email verification and lifted all bans but the problem is still there. I have checked in vb options > banning options and everything is fine. There are no IP's banned. I have also checked the usergroups and everything looks fine there as well.

What would cause this and how can I correct it?

Thank you for your time.