I setup a full scan of my hard drive. Upon restart the checkdisk program starts and that is where my problem begins. It checks ok through steps 1,2,3,4 but freezes at 83% on step 5. PC is locked cannot do anything. Power off and on again, checkdisk starts again, try hitting any key to cancel but it does not recognize the keys and starts the scan over again and with same results. How can I cancel the scan and restart my windows os?