Would like to be able to "lock" a group to prevent changes to the group. This would pevent other administrators from adding users or making other changes to a group with out first explicitly unchecking the "prevent changes" option. I find that sometimes users are getting added to the department level group where they should be in a sub department. Locking a group would prevent someone from adding people to groups at the wrong level. If they attempt to add someone to a group that is locked an error message should be displayed.