OEM Product ID Not Accepted During Reinstallation

When you attempt to reinstall an OEM version of Windows, you may receive one of the following error messages:

• INVALID PRODUCT IDENTIFICATION NUMBER The number you entered is not valid. Please make sure you typed the correct number of digits, including dashes if appropriate.
• CERTIFICATE OF AUTHENTICITY The Certificate of Authenticity number you entered is not valid. Number entered : <number you entered> You cannot complete Setup without it. To return to the previous screen and retype the number, click on the re-enter button.

You did not enter the product ID correctly, or the product ID originally entered on the computer does not match the number being entered.

You Did Not Correctly Enter the Product ID

You need to type the OEM Product ID number from the Certificate of Authenticity correctly. This number can be found on the front of the Windows booklet included with your computer. Enter the number as follows:

The Certificate of Authenticity is your assurance that the software you purchased with your computer system is legally licensed from Microsoft. If you have any concerns regarding the legitimacy of your Certificate of Authenticity (or if you do not have one), call the Microsoft Piracy Hotline 1-800-RU-Legit (in the United States or Canada), or contact your local Microsoft Subsidiary.

Product ID Number Does Not Match

When your computer was manufactured, your manufacturer entered a Certificate of Authenticity number other than the one that is printed on your Certificate of Authenticity. Therefore, the numbers do not match and the software cannot be reinstalled.

They only way to solve this is to enter the number that the manufacturer used instead of the one that is printed on your Certificate of Authenticity. You should be able to start Windows in Safe mode in order to find the original number. Use the right mouse button to click My Computer, and then click Properties on the menu that appears. The number you should enter should be listed. If you can no longer start Windows, you should contact your computer's manufacturer for more information.