I've seen this error once before and my guess (based on the previous person's experience) was that the group's page was being edited, but the time it took to edit exceeded the session timeout and so things got a little confused. Normally you just navigate to the Group's profile page and click edit, then edit its details. If your details are now set as some of the group details then I apologise, but you will have to manually fix them while we try and get a fix in place.
cheers, Chris Maunder The Code Project | Co-founder Microsoft C++ MVP