That's interesting! Is the sub powering the satelites, i would assume it is? If so than try this. Go into control panel, click on "sound and audio devices" here depending on your audio software, yuo'll get windows stadard or proprietory sound card software, you should be able to see if it may have a mute function. Have windows test your sound card it will say "this device is working properly" if it's not your sound card. Also check to see if you have connected into the inputs in the back of your sound card correctly.

This should work!
Remove the sound card drivers and then reinstall "this should resolve your problem"