Why would a three-year-old, completely legitimate install of XP Home come up and ask to be reactivated? No hardware changes. Nothing.

I am having difficulty getting straight answers out of the user. But it seems that there was a loss of Internet connectivity but LAN access was OK. Then on reboot..... Please activate Windows. But activation won't work because there is no Internet access.

The WPA.DBL file exists but its size is way too small and the time and date stamp on it are too new.

I have checked the drive for viral/trojan infections. It is clean. There was some relatively innocuous spyware. The Hosts file is OK. Nothing obiviously wrong.

System Restore is not working.

The obvious choice here is to do data recovery, followed by a clean re-install.

But I am curious. I have not encountered anything exactly like this before.

An opportunity to learn.....

Any ideas.