I reinstalled xp to fix a major problem with my laptop (a virus caused me to see the blue screen of death every time I turned on the laptop and prevented me from passsing the loading screen of windows xp, I posted the problem here). Now I cannot log in. When I try to log in it says "this copy of windows must be activated with microsoft before you can log on." There is only an empty blue screen with a mouse and I cannot open windows task manager to start explorer. I have the product key on the bottom of my laptop on a sticker, but I was never asked to enter it. What can I do? Note: I am using a different computer right now.