I'm having the same exact problem after upgrading to 7.3 a week ago. Thanks, sirdude, for the SQL queries. New members are supposed to be put into the Users group by default, as that preference is set in the control panel, but that's not happening. They show up in the User List, but cannot be found by searching from in the control panel. Help!

Also, one user, even after applying sirdude's queries, is still unable to do anything but view, even though she is assigned to the User group. ??