Can anyone think of any legitimate reason why a group in AD would have ex members re-joined. Reason I ask is I check our group membership who can access our files on a file server once a month to check nobody has been added to the group. A couple of times now I have noticed an ex employee who still works in the business but elsewhere has been relisted in the group membership, when they have 100% been removed before. I wondered any AD type maintenance that could cause this by mistake? It’s almost like the group has reverted back to a previous state/backup. Any theories how this could occur?