Thanks for the suggestion, Paul. I have not tried this but am loth to do so, because when I click on Help\Detect & Repair (in Word), I read that I shall lose (amongst other less-important things):

• The security level for each application
• [My] username - and I assume my password

Because I bought the computer secondhand I have no idea whether there is an Office username and password and if so what they are. I do not have the installation disks (if they were to be requested).

Do you know of any explanation for this sudden request for validation? What the message actually says is "You must activate your MS Office Prof. Edition 2003 installation to function properly with the recent changes made to your computer hardware". I absolutely have not changed anything about the computer. I don't even know how to take the cover off.