Windows 7, Build 7600, This Copy of Windows is not genuine

This is very annoying when you gets an error like "This Copy of Windows is not genuine" on Windows 7, this is because either you are not running genuine copy of Windows or your license got expired, there is also chance that a windows update can cause this problem, in all these three cases you gets error at the computer start up that Windows is not genuine, and also computer background changed to black screen. If you have tried entering CD Key again and again or used any software to crack windows activation with no luck then this tutorial if for you.
Please note that this is just a educational tutorial for the people who bought original windows and still getting this kind of error or people who want to buy windows but are not able to buy at this point of time.
We highly recommend you to buy genuine windows and do not support any kind of piracy.

I have a Windows 7 laptop.  Generally I am pretty pleased with it.  Not as pleased as XP, but much more pleased than that claptrap piece of junk called Vista.  Windows 7 still craps out occasionally, but a reboot (sometimes removing the batteries to do so) fixes whatever ails it.  However, I got a shocker the other day.  After re-booting, it told me that my copy of Windows was not genuine.  Windows 7, Build 7600, This Copy of Windows is not genuine.  What the hell?

Well it turned out that the fix was relatively easy, but still disconcerting.  Click on the start menu. Open up All Programs > Accessories.  Right click on Command Prompt and click on Run As Administrator.

In the command window, type in:  slmgr -rearm

That should fix it.  Another reason to think that Microsoft is a buggy piece of crap.