I just started having this problem. I have re-installed the drivers etc - but I have to turn the volume off in order to prevent the feedback. (i.e. I can't use my speakers or mic at all)
I am running RealTek audio on a Toshiba laptop. I recently changed the settings in order to get Skype to recognize my speakers and mic. That's what started it. But now that I have changed them back it is still a problem. It's really bad when I close my laptop. I have to snooze before closing or the screeching is unbearable. I have also noticed that the sound of me touching my computer (typing etc) is now amplified which it never was before.
What I did was Under Control Panel>Sounds and Audio Devices>Audio Tab>Sound Playback>Volume>Properties I checked Mic Volume and BC Beep. Then under Control Panel>Sounds and Audio Devices>Audio Tab>Sound Recording>Volume> Properties I checked Stereo mix. As I say - I have now unchecked all of these things and I am still having the problem...
HELP!