OK. So I'm navigating the options in AppleTV. I scroll over to "Computers" then down to "Settings". When I hit Computers, all of a sudden random songs from my iTunes music collection on my MAC! start playing over the stereo speakers, not the TV. (AppleTV isn't connected to the stereo.) For the life of me, I can't figure out why one should have anything to do with the other.
The computer is picking up the signal from your remote. Go to system preferences - security - general. Click on the lock and go to advanced. Check disable remote control infrared receiver.