There are obviously many things shutting down besides SD w/ AV, but nothing visual. All programs on the desktop were closed before shutting down.
This morning after a few more faulty shutdowns and the accidental discovery of a symptom that proves Vista is still active, it has been deinstalled.
Guess what? Shutdowns work... (no surprise there)
The symptom that proved Vista is still active waiting for something, was that I discovered that my mouse cursor was still active on the right display of my dual displays. It cannot be seen on the left "Shutting Down" screen, but it moves on the blackness of the right screen. Since Vista was running the driver for this, Vista was still active.
This is one thing that cannot be blamed on Microsoft. This is a programming issue for the services for SD. At the very least something like a poll every 10 seconds or less could have been done to see if the system shutdown flag was on. But the best thing would be for the program services to respond to requests to shut themselves down. And probably there is a way to verify that the request came from the system and not some virus program (strong names, digital signatures and the like...).
Here is more info on shutdowns (and I'm sure there's lots more):
http://msdn.microsoft.com/en-us/libr...77(VS.85).aspx
For now: Auf Wiedersehen (Heidi Klum)