New members creating usergroups before verifying accounts

[LostInCyberLand]

I am having a problem with new users creating user groups and showing up as having visited the forum in the last 24 hours, yet when I search the members list they don' turn up, and can only been seen in the CP Admin control panel, but show up as members who have registered, created a user group, but have not followed through with e-mail verification to verify their account.

I checked the e-mail and it is a spammer e-mail address. So how do I stop this from happening? Turn off the user group function? And how do I do that? Thanks.