If you have a Windows XP Professional and your shutdown process is very slow (you must wait minutes before shutdown command and computer is really powered off) is possible the computer cache try to empty virtual memory, and ibernation cache. This option is usually turned off by default, but third parts programs can re-enabled it.

Open, from start -> run, gpedit.msc
With this hidden tools of windows xp (only professional edition) navigate on left tree to:
Computer configuration – Windows Settings -Security Settings -Local policies – Security options.

Now on right panel, search the “voice”:
Shutdown: Clear virtual memory pagefile
and be sure the value is DISABLED

Now restart your computer, and try re-shutdown pc.