I've spent countless hours trying to fix this. It started out with me wanting to enable the "stereo mix" option and so following a youtube video I proceeded to updating the driver using device manager > update driver and after restarting, I received this error. I then downloaded the newest driver of the manufacturer website (realtek hd audio) realtek.com and installed it. Mind you, the stereo mix option did in fact show up, although I couldn't make use of any audio since I was getting the "no audio output device is installed" error. All this time, I can still see the mic/line-in inputs, and headphone/speaker outputs in the sounds (control panel). I have tried uninstalling, reinstalling, and using the roll-back option for drivers. Although from control panel, I managed to uninstall the sound card software for realtek. Between all of this, after any sort of install or uninstall I also restarted my computer. I downloaded the drivers from the HP site (PC manufacturer for my comp) and the Realtek site (sound card creator) and all of them are giving me the same results. Furthermore, I even tried the System Restore and it wouldn't work complaining about an anti-virus when all of mine are already disabled. I checked what the System Restore would affect too and nothing for my driver was in there as far as I know. I'm really not sure what my options are now, and it's sucks not having any sound. Please help me out! Thanks! P.S. For the record, my computer is the HP Elite e9180f and I run Windows 7 x64.