You may be a victim of software counterfeiting

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My father-in-law experienced a problem on his PC with a message appearing informing him that the copy of Microsoft Windows on the system might not be valid. The PC was purchased new from a seller on eBay with Windows 7 Professional preinstalled and there had not been any issues with the system when it arrived and for a long time afterwords. I scanned the system for viruses with Norton 360, but did not see an indication of that being the cause of the problem. I then ran Windows Update from Internet Explorer by selecting Tools and Windows Update. After choosing to install the available updates, I saw the following message:

Some updates were not installed

Restart now to finish installing updates.

Succeeded: 1 update
Failed: 1 update

Error(s) found:

Code 643   Windows Update encountered an unknown error. Get help with this error

Windows Can't update important files and services while the system is using them. Save any open files, and then restart the computer.

I also saw a window with the message below:

You may be a victim of software counterfeiting.

To use all Microsoft Windows® features, such as all updates from Windows Update; get the latest updates; and receive product support, your copy of Microsoft Windows® must be validated as genuine.

Go online and resolve now

You may be a victim of software

When I clicked on the "Go online and resolve now" link, I was taken to a Microsoft website which displayed the message below:

Enter a genuine Windows product key.

The product key used to activate Windows on your PC is already in use on another PC or has been blocked by Microsoft. Not to worry, we can help you with that.

After the purchase of a new product key, I clicked on the Start button, then right-clicked on Computer and selected Properties . At the bottom right-hand corner of the window next to the existing product key was a link to "Change product key". I put in the new product key, but during the verification process still received a message that the copy of Windows might not be valid.

Firefox was the default browser and was apparently being used for the verification process. I noticed that the "Windows Activation Technologies Plugin for Mozilla" was listed under "Unknown Plugins". I made Internet Explorer the default browser, so it would be used instead of Firefox for the validation process. I then entered the product key again and this time I saw an "Activation was successful" message.

I then tried installing all available updates. Again, I saw the error message "Code 643 Windows Update encountered an unknown error." But when I rebooted and ran Windows Update from within Internet Explorer again, this time I was able to successfully install all available updates.


  1. Update your Windows product key   Windows 7
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Created: Saturday October 12, 2013