XP does not shut down after Fevruary update (automatic)

Both my computers (running XP professional) have automatically updated in the
last two days and in both cases the computer did not shut down when I logged
out. Despite warning after 12 hours I removed power from one and when I
switched back on it had lost a lot of settings and I had to reinstall all my
sound devices. Presumably the Registry was inperfectly saved. The other I
have left on, frozen at the shutting down screen. Is there anything I can do
to force it to shut down gracefully?