Check this LINK to see if it helps.
I have recently used Win Vista and removed it from a secondary driver on my machine. Now having reverted back to XP when I go to click shut down the computer waits and goes idle displaying the hour glass mouse icon. This has never happened before, and I have never experianced this type of problem to know how to fix it. When I click shut down from Task Manager the computer immediately performs the operation. Any help would be appreciated.