Let's take a shot here:
Often XP's exit sound file gets corrupt and if it does not run then XP won't shut down. I am not sure based on what you have told us so far if this is the issue or not, but let's see:
Go to:Start > Control Panel > Sounds, Speech, and Audio Devices > Sounds and Audio Devices > Sounds tab
Under Program Events
scroll down until you see Exit Windows
. Highlight Exit Windows
by clicking on it once. Then under Sounds
. Click Apply
and finally OK
Reboot if possible, or shut down computer and restart manually. Once it is up and running, shut down computer by going to Start > Turn Off Computer
. See if it will shut down on it's own now.
If it does, the only difference will be that you will not longer hear the 2 seconds of music that XP usually plays as it shuts down.
Oh, and welcome to BC!
Edited by Albert Frankenstein, 16 May 2006 - 12:49 PM.