A loyal Windows Tweaks reader (Daniel R.) emailed me this morning with another solution to the Windows XP Shutdownguide attentive.
If the PC with XP, Vista or Windows 7 simply gets stuck when shutting down, the following solution may help: If you are connected to the network/Internet via cable (LAN), you should switch off the "Wake-up" function of the network adapter.
It enables the PC to wake up via the network. If you don't need this, you should do without it. And this is how it works:
1. right-click on "Computer" (My Computer on XP) and select "Properties".

For XP, click on "Hardware".
2. continue by clicking on "Device Manager". In the next window, open the "Network adapters" category and double-click on the network adapter. You can usually recognize it by its name, such as "NVIDIA nForce 10/100/1000 Mbps Ethernet" or "Marvell Yukon PCI-E Gigabit Ethernet Controller":

3. search for the "Wake-up function". Switch from "Magic Packet & Pattern Match" (or "Activation by Magic Packet") to "None" (or "Deactivated").

Click on "OK"! From now on, the shutdown should work perfectly again.
Alle Tipps haben bei mir nicht geholfen. Habe dann ein 2. Benutzerkonto angelegt um evtl. Profilmacken zu vermeiden. Dann noch den „User Profile Hive Cleanup“ von Microsoft als zusätzlich Dienst installiert. Den Prefetch-Ordner geleert, NVIDIA-Grafiktreiberleichen entfernt, da das shutdown-Problem gefühlsmässig nach längerem Lauf des Bildschirmschoners auftrat, ja, auftrat. Jetzt scheint Ruhe zu sein, der shutdown klappt endlich wie gewünscht. PC: HP Pavilion a4603w