Apple TV picture out after EyeTV installation

Question

I've had an Apple TV nearly a year. This past week, I set up an EyeTV system on my iMac (running OS 10.5.2) to record TV to send to the Apple TV (running the Take 2 software update). I got an EyeTV 250 Plus with EyeTV 3.0.1 software and a Turbo.264 stick running version 1.2. Things ran OK for a day or so. I did have to reset the Apple TV twice, which was unusual, but after this, things worked fine. Today, however, the Apple TV is displaying no picture. My TV says it has an "invalid format." I am able to hear the start-up music and am actually able to stream iTunes to the Apple TV via AirTunes. But there is no picture.
I've tried forcing the Apple TV into selecting a video mode (menu-plus button on Apple remote). It briefly shows the video mode 480p, but I'm not able to maintain the picture though I've tried hitting the play button, the menu button and doing nothing. It flashes green, then goes to black and the TV indicates I'm in "invalid format" again. I've reset and restarted and plugged and unplugged HDMI cables several times to no avail. I'd run diagnostics or do a factory restore, but I'm not sure how to do that without being able to see the screen.
I'm looking for ideas.

Answer 1

Though I didn't have any spare HDMI or component cables (and didn't want to invest just for troubleshooting), I found old composite cables and hooked the Apple TV to my TV using the component jacks. And it worked. I was able to switch Apple TV to 1080i again.
And in fact, these cheap composite cables I had lying around work better with my Apple TV than the HDMI cable I had to buy special. With HDMI, there was always a delay each time I switched to Apple TV—the TV displayed a "connecting" message for several seconds. Then, once it connected, several seconds later, the TV threw up a screen-obstructing warning that the audio was not compatible—even though it worked. Now, with composite cables in component cable jacks, there is no delay when switching to Apple TV and no warning message from the TV about audio. (The picture quality may even be better, but that may be because I've been looking at 480p plus I'm bleary-eyed for lack of sleep troubleshooting this.)
Those I've discussed this with say that EyeTV had nothing to do with my problems. I don't understand why they say that, but because they sound truly sincere, I will continue to test EyeTV exports to the Apple TV to see if the problems crop up again.