I just download a Windows 8 "en_windows_8_x64_dvd_915440.iso" from technet and try to install on a Sony NB. I delete all partition on NB and boot from Windows 8 DVD and start install. On beginning of installation it ask me enter the product key. I enter the key get from technet, it wait a long time (about 5 minutes) and get "We couldn't verify product key. Please check your installation media." error. Cannot continue. What happen ???