The Registry changes are probably being undone by 1) an automated process that is triggered when you use a domain login -or- 2) an IT process (perhaps manual) that periodically undoes such things to make sure SMS keeps running. So you could try just not logging in to that machine with domain accounts (make local accounts just on that machine for whatever you need).

But the sure-fire fix is to remove Domain Admins and any domain users (or other domain groups) from the Admins group and make sure there aren't any other local groups that have been given special access rights. If you need Admin privilege on the machine, then create a separate non-domain account for that. Then the IT department won't have privilege to undo your Registry changes.

        - tye (but my friends call me "Tye")