I built a gaming PC back in November and installed + activated Windows 7 Ultimate on November 26th and it actiavted fine (I had to do it over the automated phone because it had been on another computer before). Now today, 6 months later, my computer says in the bottom of the screen: this copy of windows is not genuine build 7601. I don't know why this has happend as the activation has been fine for 6 months and I actuallty have got the OS legally. I've tried re-activating and doing to automated phone activation and none of them work.
Is there a way I can fix this, because I don't want to buy another one when I have already bough a copy legit.