Sweetone, not so strange.
Going to the front page of our forum and typing in "Unauthed player" in the search box brings up many discussions.
99% of them were resolved (1% never responded after we prompted), and usually were due to a mixed ULib/ULX versions (SVN of one or not the other, not using absolute latest SVN from our site (not Xenon or another download site, or dual installs on client), incompatible addons (DarkRP, older Wiremod, Assmod on local machine)
If I were you, since this is a client (you) issue only, I'd uninstall Gmod on my local PC, make sure my local addons folder was wiped, remove all addons if not, then reinstall Gmod and rejoin the server.
If that didn't work, with all the problems you've been reporting over the past few days, I'd shut down my server... do a fresh server install after removing all Garrysmod folder files, then get latest SVN from our SVN (again, nowhere else, ulyssesmod.net/ULib/trunk and ulx/trunk only).
No other addons. ULib/ULX only. Not even Xgui or our other projects.
Don't use any backed up files.
Start server. Join. Use your rcon to adduser yourself as superadmin.
Leave server.
Restart server.
Rejoin. See if it sees you as superadmin. Check !menu.
If that doesn't work, give us eact error messages.
THEN, and only then, add one addon back at a time, even ours, restart server, test.
Once you've found the culprit, give us the name of the conflicting addon.
Follow the instructions from our FAQ "Having trouble with access" only AFTER you've done all the above.
http://forums.ulyssesmod.net/index.php/topic,383.0.html