David ...... you need to find the audio drivers for the Sound card for your machine. I assume that you own a Dell computer and if you go onto the Dell site with the details of your computer, you can download the latest drivers. Normally, the sound processor is a separate chipset on the motherboard .... an example and probably the most common is Realtek AC 97. Have you had a look for the sound drivers on a CD that came with the machine?
Chris
September 2007