Windows Validation / Genuine Advantage It is the process by which Microsoft determines whether the operating system loaded on the computer is a legitimate copy of Windows or not. If the version of the operating system does not pass the Windows Validation Process, then the computer will not be able to download security patch from Windows or install other software from Microsoft that require a genuine validation process.
Version of Windows does not pass validation In this, you need to submit the proof of purchase of the operating system to Microsoft. You will have to fill up a report with the details of purchase. In return, you will get a legit copy of the operating system from Microsoft. Else you can call Microsoft's toll-free number, follow the voice instructions and get a special code to validate your copy of the operating system.
For the customers who have purchased a used computer, the only option is to buy either the Windows Genuine Kit or the legal copy of Windows operating system.
Legal copy of Windows fails validation In this case you need to go to www.microsoft.com/genuine/diag/ to diagnose and fix the validation problem.
Security update for Windows Genuine Advantage not installing This can happen if ActiveX control is disabled. To fix this, open Internet Explorer > click tools > click programs tab > click manage add-on > find Windows Genuine Advantage tool & click it. Check whether it is enabled or not. If not, click Enable and click OK twice. Close the Internet Explorer and retry to validate the Windows operating system once again.