Try this...
1. Right click on the speaker icon on the desktop and then click on "Sound".
2. Click on the "Recording" tab and then click on the correct device in the list. Make sure your headset is plugged in.
3. Next click the "Configure" button at the bottom of the window and check the way it is setup.
4. Should that not change it, then click the "Properties" button.
Once that is done, should it continue, you may need to check the systems sounds rather than the mic settings.
5. Go back to the window with the "Recording" tab and click on the "Playback" tab.
6. Click on your headset in the list and then click the "Properties" button.
7. On this new screen click the "Enhancements" tab.
8. Now check to make sure it is not set up to use...