When I play something in iTunes locally, it automatically plays on the AppleTV

This makes no sense whatsoever.

In Lion, I load up iTunes and begin listening to my music. Whatever I listen to or watch, it turns on the AppleTV box and streams it to it.

How do I stop iTunes from doing this?

Here's the caveat: I want the AppleTV box to connect to my iTunes in case someone wants to watch a TV show, movie or listen to music I've purchased from iTunes. I just don't want my local iTunes to control the box.

Until upgrading to Lion, this NEVER happened.