I'm having the same problem using Joomla! 1.0.11 and CB 1.0.1.
What happens is that I try to change anything on a user as superadmin in the backend, but it prompts me for the password.
If I happen to know the users password and type it in, I'm told the user already exists and are put back to editing the profile.
Very thankful for any pointers, would be a pain to reinstall CB (again) at this time...
- Icky