Would this be of any help, Zoe? I copied part of the info from Symantec's virus description. It might be way off, but is there a chance your computer is infected with this or a similar virus?
When a document infected with W97M.Tchau is opened or closed, the macro virus performs the following actions:
Disables Virus Protection in Microsoft Word.
Infects the Microsoft Word global template, Normal.dot.
Deletes the files:
Displays various pop-up message boxes.