Eloqua - I can't remove a security group from a user settings _ Do default security group exist?

Hi,

I set up a new Eloqua profiler user with a tailored security group to apply some content access restrictions (labels).

When saving after having selected that group, a not selected security group is additinally added by default. If I remove it from the "selected security groups" box and save, it instantly reappears. ... No way to remove it.

I can't find where the default security groups are set and if I delete it, It will be removed from the rest of the users.

Has anyone had this same problem? ... Any thoughts? 

Thanks