Hmm that's interesting, those steps almost always re-install the sound card properly. Dell does have two drivers listed on their support site, but I was having you use the latest version of the drivers according to their web site. Assuming there is some corruption with their drivers lets try one more time with the other drivers.
Download the below file and try installing it on the computer to use the earlier version of the drivers.
ftp.dell.com/audio/R264250.exe
* Before installing the above file make sure to go back into Device Manager, and uninstall each of the Sound Video game controllers, any "Other Devices" and any device with an exclamation mark on it.
If that still results in the same situation, try the below steps and restore your computer back to an earlier copy of Windows.
1. Click Start
2. In the search box type System Restore
3. Select Choose a different restore point
4. Check the box for show more restore points.
5. Select the oldest restore point and click Next
Let the computer restore to an earlier point and restart the computer.
If you continue to have the same situation then either there is a serious corruption with the Windows registry or other files are residing on the computer that are conflicting. You could also try running ccleaner to clean out any registry issues.
http://www.piriform.com/ccleanerThe other possibility is that there is a defect with the sound card on the computer, and that hardware defect is what is causing all the problems. Because this is out of warranty you could be 100% by running a diagnostics on the computer to check for any hardware defect and also erase everything and re-install everything back on to the computer. Both diagnostics and system restore are available by pressing the F12 key as the computer is starting up to access the hidden partition.