The groups.txt file you were using may have not been standard, or got corrupted during the convert to the new UCL system.
See
http://forums.ulyssesmod.net/index.php/topic,4134.0.htmlFor now, backup and then delete your gmod/data/ulib/groups.txt and misc_registered.txt files.
Make sure you're superadmin in the standard gmod/settings/users.txt, then start your server back up.
See if you get errors.
It's possible you messed up an edit somewhere. (then again, its SVN, and possible we messed up somewhere, but, its hard to troubleshoot when our beta code has been edited to fit one's own needs - legal, sure, but still difficult)