This is a handy tip I found on the MS TechNet forums which I belong to, so I though I might share it. PROBLEM: My computer recently got a virus and I had a great deal of problem getting it off. It prevented me from connecting to the internet. My computer has now been cleared of viruses but now says I don't have a genuine version of Windows 7(I think it was when I first got an internet connection again). However, it wants me to reinstall which I really don't want to do. I have the installation CD and the key given with it. Can someone link me or explain to me exactly what I must do to reactivate windows 7 without needing to reinstall. Much appreciated SOLUTION: Problem solved, and for anyone else who is interested. Hit the Windows Key and the pause/break key at the same time. Click change product key - enter / change to a valid key when prompted and then wait for the online activation to complete. You should now have a valid version of windows. P.S Microsoft should really mention this alternative when explaining about reactivating a genuine version of Windows 7. Note: I did edit this a little for ease of readability.