pirate software message ?

Hi

I've recently started getting a message appear stating "you may have been a
victim of pirate software" appear on my desktop. It asks me to enter my
verification code & then goes online to verify my version of Vista.
Everything works fine then until after a few weeks when I get the message
appear again & have to go through the whole registration process again. My
Vista is genuine (honest) but I appear to be getting this since one of the
updates (but not sure which one). Has anyone else had this problem.

Thanks

Gaz