I've got the same problem with Apple TV 2 and Phillips 37PFL9604H. Both have the most recent firmware.
My Phillips TV has 4 HDMI ports. I'm using the other 3 for:
- XBOX 360: no problem at all.
- Pioneer DVR-550HX-S: no problem at all.
- InOut Mediacenter 4G: no problem at all.
But when I use Apple TV 2, after a few seconds the screen goes blank. When it returns, the normal black background has been replaced by a green one and all colors seem to be inverted.

I've tried using a different HDMI port and a different cable, but the problem is the same.
I use the spanish version, so maybe menu names are not exactly as I type here. I go to Settings, Audio/Video, HDMI output (it shows "Auto"), I select that option and after a couple of seconds everything is OK. But a bit later the problem appears again, randomly.
It's more likely to happen when I use airplay from my iPad or iPhone.
After a recent Apple firmware update the problem seemed to have been fixed, and I was able to see the entire movie "The social network" without any problem. But no way to use airplay even for 5min videos without interruption.
Before I bought my Apple TV, I had the same problem playing a movie from iTunes from my Dell computer and conecting to the Phillips TV by HDMI.
I love Apple TV as a product, BUT IT'S A DISAPPOINTING EXPERIENCE. IT JUST DOESN'T WORK. I love my Phillips TV also, and I don't want to change it because it works fine with all the other products, not only the three connected by HDMI, but also three more connected to non-HDMI input ports.
Will this still happen in the new iOS releases?
Thanks