Hi
( Assuming XP )
Click on Start > Run ....type in ....mmsys.cpl ......ENTER
Click on the Audio tab
Confirm that the sound card that you want to use is displayed in the Default Device box under Sound Playback.
If the sound card that you want to use is not displayed in the Default Device box, click the sound card that you want to use.
( Down arrow to display options )
Click to select the Use only default devices check box, and then click OK.
You will probably need a re-start.