Please go to http://www.microsoft.com/genuine. Click Validate Windows. If there's any error code, please note it.
Next download Windows Genuine Diagnostic Tool from http://go.microsoft.com/fwlink/?linkid=52012. Save MGADiag.exe in your desktop. Run MGADiag.exe by double-clicking the file then click the Continue button. Once the diagnostic is done, click Copy. Post the following in your reply here:
1. Paste the result of the diagnostic after you've copied it.
2. The error code you got when validate windows from http://www.microsoft.com/genuine