Problem VIP user
Thorough investigation will usually show the one single user just didn't read the memo and is the only one still trying to connect to the disconnected system. VIPs have a tendency to think that memos to all don't apply to them. Just charging that VIP with all unnecessary overtime caused by him (never found a female in that particular group yet) is very satisfying and will make sure the project comes in within budget, but that is about all you can do about it.