Re the "Norton problem with XP SP3" (a couple of posts up) - we received "special" updates from Norton today on four computers. Updates are automatic (daily) if they don't require you to reboot, but usually Norton asks if you want to download anything that will require a reboot. This update did require reboot to complete the installation.
While the update didn't indicate why it was coming I did note the presence of an "update to foreign security certificates" that could mean that they convinced Microsoft to "certificate" SP3 registry deletions and part of the update was to allow recognition of Microsoft as having "authority" to f**k with modify the registry entries.