System audio plays over microphone all the time

[MrGroggle]

Hello there.
I am fairly tech savvy, but this one has stumped me. When using Skype or other VOIP programs, any audio I happen to be listening to is played, sometimes incredibly loudly, over my microphone, without me wanting it to. It makes having a Skype call almost unbearable, as I cannot play any games with gunfire or loud noises.
Some facts:
I am using Realtek ALC887 audio drivers, and I do not have a sound card. My headset is a Turtle Beach x12.
My Realtek does have a tendency to act up, in that it sometimes thinks I have things plugged in when they're not, and vice versa.
If I am playing a song from anywhere (YouTube, iTunes, etc) it transmits it over my microphone. If I unplug the green jack, this stops.
Stereo mix is disabled, but I have tried enabling it and turning the volume down to minimum, with no change.
Thanks,
MrGroggle

 

[soundguruman]

your mic is plugged into the speaker jack.

 

[MrGroggle]

Well, I'm 100% sure it's not. I've checked all the jacks, and they're definitely in the correct sockets. If it were the other way around, I wouldn't hear any audio, and as it is, the headset is working fine.