Right. Try doing both of the following.
Right click the little speaker icon in your system tray. Click on Volume control options
. Make sure you have the first option checked and the second option unchecked. Then check both speakers listed under Sound devices
and see what happens.
You have an N/A listing in your System Specs for your Sound Card so I'm assuming
that you have the default Realtek HD Audio card that comes with your specific motherboard. Try updating the drivers for it. You can find the Realtek drivers/codecs at either of the links below. Realtek High Definition Audio Codec) - CNET Download.com
Realtek HD Audio Drivers