When you describe "clear room audio", do you mean just a quietening of the background noise or it is picking up sounds from the internal microphone and relaying sounds from inside the room?
The 'digital' noises are nothing encrypted, they are the normal workings of the logic signals, some will be from timer circuits and repetitive, some will be from things like the network interface and video circuits which change according to the program flow.
There are legitimate reasons why it could modulate a carrier signal, even if unintentionally but it would be unusual to do so because the microphone signal is normally digitized early in the circuitry. In it's digital format, even if you could hear the signal on the radio, it would be nothing more than a constant buzz with little or no indication it was carrying any sound at all. For now, you should be able to turn the HD audio on again, assuming you use it for other purposes, but mute the microphone input from the mixer control panel (I'm not using Windows so I can't tell you exactly where the control is).
I think that's a different thing Brad.
The same philosophy applies to all other programs that use the microphone. Make sure none of the "social media" applications like Skype, Yahoo messenger, Ekiga and the likes are started automatically when the computer boots up.
You can locate the source of your bug with a small loop antenna and SA to pick up near field emissions. Let the diameter of the loop be same or less than gap of about a few cm.
You might also try a speaker as an antenna for near field sensing using the coil to increase sensitivity.