problem shutting down computer

It could be waiting to end services ....
HOwever ..after setting a restore point you could try these two:
Start Regedit.
Navigate to HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Control.
Click on the "Control" Folder.
Select "WaitToKillServiceTimeout"
Right click on it and select Modify.
Set it a value lower than 2000


XP shuts down too slow?

Open your favorite Registry editing program and head to :
HKEY_Current_User\Control Panel\Desktop and look for AutoEndTasks. Default is "0". Set this value to "1".

 

Check taskmanager and see what services are running when you want to shut down ....could be waiting for firefox or something else to finish closing down

 

For a one-click method to quickly shut down or reboot your system without the fuss of going through the Start menu, make use of the Shutdown command, a command line utility in XP.

Here's how you can set up a restart button on your desktop:

1. Create a shortcut (Right-click on desktop, select New > Shortcut).

2. For location, type the following:

shutdown -r -t 0

3. Click Next, enter a name for the shortcut ("Restart" is appropriate), and click Finish.

When you click your Restart shortcut, Windows XP will reboot *automagically*!

The "-r" switch tells XP to reboot. If you'd like the shortcut to shut off your PC instead, change it to "-s"; to simply log off, change it to "-l". The "-t 0" sets the timeout (in seconds), so up this value if you find the need for it. To force running applications to close, add "-f" -- be careful with this one!

For more information on Shutdown, type "shutdown" in a command prompt window (Start > All Programs > Accessories > Command Prompt), or search for Shutdown in Windows XP's Help and Support Center.