Comment Failure on many levels (Score 5, Informative) 123
When I get such a ticket, I drop what I was doing and immediately disable their AD account. This blocks them from logging in to any work computer, and it also cuts off access to the VPN. There's a number of other steps to take to completely clean the user out, but disabling their AD account effectively locks them out and the rest of the stuff can be handled in due time.
The sort of thing described in this article would not happen under my watch.