What you're experiencing, Fawlkon, is called volume attenuation. Skype will often lower the volume on other applications when you join a call, so that you can hear the people in your call over your music, movies, etc.
I still have no idea what would cause the problem you're describing. Specific distortion like that is difficult to troubleshoot. I'd still say that as unlikely as it sounds other people's mics are just **bleep** and their 'conversations' is them talking back and forth about how they can't understand each other(or maybe just background noise).
If you'd like, you can add me on Origin and we can join an MP game. I know for a fact my mic works fine, as I use it everyday. It could at least help eliminate the 'everyone's mic sucks' theory.
I sent you a friend reqest, but my mic is working fine now. Here is to hoping it stays that way...Game on!
