Windows 7: Windows 7 not genuine

I am running 2 home computers on a network, the main computer I just purchased recently running windows 7 which was pre-installed.
The second computer is running windows 7 which I purchased from PC World.
Yesterday when I tried to start up computer 2 I receive the message:
This copy of windows is not genuine followed by a build number.
Is there any way I can rectify this without doing a full reinstall.

thanks jack

Try these one by one:

1) Where it says, "Go online to resolve....", do so, many a times that solves the issue.

2) In installed windows updates (look in left pane of Programs anf Features->View Installed updates), locate kb971033 (thats WAT), uninstall it, if it lets you. Reboot, then go to the microsoft genuine website and let it install WAT and validate.

3) Sudden random non genuineness can also be the result of a permissions issue in a registry key. Follow the steps here.

Genuine Windows 7 Became Pirated? Make It Original and Activated Again - Tweaking with Vishal

4) If none of this works, download and run mgadiag.exe tool.

http://go.microsoft.com/fwlink/?linkid=52012

Click on the Copy button, paste to notepad, save as text file and upload it here.

5) As a last resort, you call call MS.

Activate Windows 7 by Phone

The main issue with the KB971033 update is that it detects changes to the Activation files within Windows. If, for example you have a pre-installed Windows 7, then it's more than likely that it was installed as Pre-Activated by the laptop provider. A Pre-Activated Windows 7, although Genuine, has had it's Activation files changed to bypass activation and put it in an Activated state.

Follow the steps above and you should have no issues


OS

The problem is:
When I bootup it tries for about 5 minutes to start windows the the message Not Genuine comes in the left hand bottom corner.
So windows does not even start, so I cannot do any of the things suggested.

jack