Windows Activation screen keeps reappearing?

Infopackets Reader Linda R. from the United Kingdom writes:

" Dear Dennis,

Thanks again for all the help in the past. I have an urgent question, however. The past two days when I reboot my Windows XP machine, I am getting message 'Windows has to be Activated within [now] 6 days', and prompts me to click on Yes. When I do this, a larger box comes up with the message, 'Windows already activated.' What does all this mean? "

My response:

That's very strange! If you have the original Windows XP install disc, you (or the person who installed XP) were supposed to enter the CD Key in the preliminary stage of installing Windows. All this does is verify that you own a legitimate Windows XP CD. After the installation, the next step is to Activate Windows, which registers your computer with Microsoft and also "unlocks" Windows.

But since Windows is reporting that it's already activated, you shouldn't be receiving this message. I think in this case, your best bet is to call Microsoft to re-activate your PC. If you don't have an original Windows XP install CD, you can explain your circumstances to Microsoft.

After sending my response, Linda wrote in again:

" Thanks again Dennis! I contacted Microsoft as you suggested. I explained that I don't have the Windows XP disc, and they very kindly agreed to send me the appropriate activation code within 48 hours! I couldn't have managed this without you! Thanks from a very grateful girl on the other side of the ocean! "