An error on AdminCP

Hi boys, i run a Vbulletin V. 3.6.8 based forum at www.forumerbase.com and each time i try to change properties of UsreGroups into my AdminCP (for example if i set the max. numbers of items the group "Admin" can store on inbox and press "update" i get this error:

The forum is fully mod and i know i should edit a file or table, but the point is: wich file or table and what edit?

Any suggestion?. Thanks

 

Try disabling your plugins:

Admin CP -> vBulletin Options -> Plugin/Hook System

Also run a file check to look for customized or missing files:

Admin CP -> Maintenance -> Diagnostics -> Suspect File Versions maybe it will help you ..