wupdater.exe error message - windows xp pro

> I'm having a problem with this executable: "wupdater.exe"
> when i try to log off or shut off my computer (XP pro)
> I get an error message stating that "wupdater.exe has
> failed to respond." it runs through a blue timer and then
> nothing happens. the only way i can log off or turn off the
> computer is to tell the process to "end now" or end the
> process at the task manager level. This is frustrating.
>
> What is this wupdater? HELP!!
>
> ChrisD
>