hi john,
Have you added or removed any software before the problem started ?
You could try to reinstall the drivers for the onboard soundcard.
To disable the original soundcard you may need to do this from the bios setup utility.
Here is a link for the manual and bios updates
in case you don't have it
http://www.biostar.com.tw/support/bios/bios.php3?model=M7VKS73 james