1 – Windows is very good about remembering the last thing it did correctly. And at ignoring the competition (Novell).
2 – You did not say – Are they having to switch from local machine back to Domain in the logon box? If so it is patching / updates that cause the switch to ‘local’ administrator. If it is ‘DOMAIN’ you have a login script exerting privileges for the ‘Domain Administraotr’ as opposed to running as the ‘system’ account.
3 – Hope this points you in the right direction.