When trying to activate Windows XP or Windows Vista system by using online product activation service provided by Microsoft, Windows Product Activation (WPA) wizard will reject the license serial or product key entered by saying the activation key is invalid or has been entered incorrectly. Then a pop up window appears asking user to re-enter the product key or activate using automatic phone system. Even if user call Microsoft phone activation hotline, the product key is still denied when entered during initial automated voice recognition system. Users requires to gives 64-number activation ID to operator or Microsoft CSR representative to get 48-number installation ID to successfully complete the activation process.

This symptom happens when users attempt to activate online over Internet using OEM CD key or product key located on COA (Certificate of Authenticity) label or sticker on PCs or laptops. This unique product keys is often unused because OEMs always already pre-install Windows XP or Vista on system they sold and pre-activate the system using a special pre-activated key to bypass product activation. Thus buyers of OEM brand computer never had to activate the system again, nor needed to enter any product key on first use. Even if you reinstall Windows again on the machine by using factory restore produce or using recovery CD provided by OEM such as Dell, HP, IBM, Lenovo, Acer, Toshiba, and etc, you won’t need a product key or have to activate Windows online or by phone.

Product key on COA sticker is only used when users install Windows on the computer using non-default factory recovery or restoration method provided by OEM. This situation can happen when you try to install fresh Windows using original retail Windows CD to avoid crappy programs often accompany OEM Windows restore image. But not many will go this path. As these keys on COA labels are seldom used, many unethical people copies and sells these COA OEM product key, sometimes together with the Windows CD and counterfeit COA. As these keys are never used before anyone, it’s treated as genuine and valid, and the Windows system is activated via Internet even though its license is illegal.

To stop this illegal practice, Microsoft has disabled product activation over Internet using OEM keys used by worldwide PC makers, and always require phone activation. Thus if you enter OEM product key from a COA label, you will be required and directed to call customer support specialists to obtain an installation ID which will override the invalid product key control, provided you can prove that your copy of Windows is genuine and legitimate by answering a few questions.

Thus if you do not like to go through this hassle, restore your computer using recovery CD or recover partition or ofter factory restore procedure provided by your OEM computer, where no product key or activation is needed. Refer to computer manual if you not sure how to do it.