Could there be a conflict between the onboard audio and the sound card (You have Sound Blaster Audigy2 zs sound card, I believe)? You may have to look for the sound card
driver here:
Creative Worldwide Support and then select windows 7 x64*, or try this (Same thing but I've already located the driver for you):
http://support.creative.com/download...wnloadId=11314 (If it says something about a server error, try reloading the page)
*ps don't download any beta
drivers, stick to searching for just the drivers