If you are getting Windows is not genuine error messages in windows 7 like this one
To remove this annoying message from your computer and to set windows 7 to its previous genuine state. Run this command on command prompt:
C:\> slmgr /rearm
Then reboot the computer after the commands stop running. you will find there will be no notifications that can bother you now.
But Remember that you have to login as Administrator for this command to run successfully.