|Go to Dell with the model number and ensure you have the latest sound drivers. If they have corrupted updating them can often fix issues.|
Also have a look in Device Manager and see if there are any errors showing (Under sound video and game controllers heading). You could try right clicking the sound driver entry and using Uninstall. When you restart the computer it will find the driver and set it up again. DO NOT let it remove "Software" if it should ask, otherwise ignore warnings.
This could well be a hardware fault (sound chip/circuitry).
Always pop back and let us know the outcome - thanks
message edited by Derek