The link for microphone fix:
http://www.zombicidal.com/guides/other/

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Microphone Stops Working Periodically

Some users experience an issue where their microphones work properly when first configured (either through the Steam panel or in-game), but then stop working after a few minutes. This is because every so often, Steam has a “useful feature” that switches your recording input to “Microphone”. It’s actually one of VALVe’s brilliant game-balancing tweaks, because then players have to minimize the game to change it back. (Okay, so it isn’t actually a tweak, but I wouldn’t put it past them.)
To fix this, download Muvixer. This is a lightweight freeware tool that monitors your recording settings and slaps them back into line when Steam changes them insidiously. The tool sits in the system tray and is highly configurable. I recommend running it at startup if you play often. Note that switching to a third-party