Comment 5 for bug 99276

I just encountered this same issue on a new Feisty (7.04) install when I attempted to create a user name of "staff". As is default in Ubuntu, USERGROUPS=yes in adduser.conf so each new user gets their own group. The group "staff" is a Ubuntu default with a GID of 50 so it couldn't be used. No messages were displayed by users-admin and I didn't figure out what the problem was until I tried to use adduser which informed me the group already existed.