Look in ubbthreads.php on line 51 (or do a case-sensitive search for "$Groups"). You will see $Groups gets assigned there... then on line 97, you will see if they are a Guest, the get assigned to group "-4-".
So, at the very least:
Guests = group "-4-"
Users = group "-3-"
Moderators = group "-2-"
Admins = group "-1-"
These get combined for various assignments, like a mod who is an admin would be in group "-1-2-"
What it looks like is that users are not getting assigned to groups... try adding this:
<br />echo "GROUPS = $Groups<p>";<br />
to the getCatBreadCrumbMenu function in ubbt.inc.php. Then go to the page and see if the var is getting populated.
