I had users recently encounter problems accessing pages and modules after I did an update of the settings. The forum this is occurring on has a total of 86 usergroups (that's after I cleared out 7 or so), more than most I might imagine.

The problem I'm seeing is that the userperms field of the adv_modules & adv_pages is restricted to 255 characters. So if you have a forum with lots of usergroups and you select all all, vBa only stores usergroup IDs up to the 255th character leaving the bottom half of usergroups unselected.