Have you tried going to the manufacturer's website (of the audio card) to see if there are newer drivers for it ? That would be a good place to start.
I guess before you look for drivers, you could open Device Manager and see if there is any problem with the card that is detected by Windows (in the DM). You can see if the device is working properly according to the dialog box. You know it isn't working right, but does Windows? You could check there. Also you can click the Troubleshooting button to see what comes up for details.