1. Click the 'Start' button from the left-hand side of the Windows task bar at the bottom of the screen. Right-click 'Computer' from the Start menu and choose 'Properties' from the menu.
2. Click the 'Change Product Key' link located at the bottom of the 'Properties' window.

3. Type in your genuine product key in the text box, then press the 'Next' button.
4. Allow Windows a moment to change your product key. You will see a progress window during this process and receive a prompt once it is complete. You may also be prompted to go to the Microsoft website for the final step.
5. Open your website browser and go to the Windows validation website that is listed in the resource section of the article.
6. Click the 'Validate Windows' button on the website to validate your product key. You may need to install a browser plug-in to complete this. Once you have validated your product key, the validation error should not show again.