usergroup issues

[Dinocanid]

That's strange. If you go into phpMyAdmin -> adopts_users, is their usergroup 4 or 6? If it isn't any number between 1 and 6 (NULL for example), something went wrong in the script.
I never got this error, even with a fresh install. Did you alter anything like group names?
After searching the forum, maybe try this fix?: http://mysidiaadoptables.com/forum/s...=membercreator
(If that fix doesn't work, put it back how it was)