Removing boot pop-up (XP)

I've been asked to remove a pop-up that appears before (or over) the user profile screen in Windows XP. After the windows logo the screen goes black and a message appears that disappears when you click ok, nad you then see the user select screen.

It's a used PC donated to a teacher who doesn't want the message appearing any more as it states that it's a government PC and that if it's not there you should call the number provided. While she legally owns it, she is worried about someone seeing it and assuming she doesn't.

I've got no idea where to start with removing it, and the only fix I can think of is to do a clean install of XP, but she doesn't want to lose office and doesn't have the back up disks.

Any ideas?

 

Try this:
Run regedit and navigate to
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Winlogon

and delete below keys

"LegalNoticeText"="Your Message"
"LegalNoticeCaption"="Legal Notice"

 

Cheers, regedit fixed it.