Are you running Windows XP?
I recently had a customer with a similar problem on an XP desktop; I tried all sorts of fixes before finding the answer in an online forum - it was a problem with the 'Software Enumerator' see the link below and look for a post by 'Jurekos'
Or follow the summarised steps below:
- FIRSTLY CREATE A RECOVERY POINT IN CASE IT DOESN'T WORK AND YOU NEED TO UNDO CHANGES -
1. Check if PnP SW Enumerator is installed on your machine (Device Manager / System devices) - it should be listed there!
2. If it is not there then we will probably solve it!
3. Locate "machine.inf" on your OS, copy it somewhere and modify it as follows:
(find "ExcludeFromSelect=*" and remove the line or simply exclude it from processing by adding a ";" at the beginning)
4. Check the "machine.inf" file for location where SWENUM should be located (mine was reading: SWENUM.CoInstallers.CopyFiles = 11 ; %windir%\System32)
5. Find "swenum.sys" file on your XP installation CD (mine was in DRIVER.CAB) and copy it to the proper location (I am not sure if it is necessary but worked for me) You could also copy this file from someone else's Working copy of Windows XP if you don't have your installation CD
6. Go to Control Panel /Add Hardware and follow the wizard towards manual selection of device to be added
7. Select Add System device
8. Select Have disk
9. Navigate to changed machine.inf
10. from the list select standard devices (in the left list) and "Plug and Play Software Enumerator" in the right list
11. Finish the installation
If it still does not work reinstall the audio adapters' drivers
Post a reply if you don't understand any of the steps listed and I'll try to explain in more detail
Good Luck - John