You see this issue to sometimes be a firmware update (sorry if I nod here and wonder why we accept that).
http://www.avforums.com/forums/lg-owners-forum/900234-37lg50-tv-lg-lht-854-dvd-invalid-format-error-tv-cant-use-hdmi-now.html may be a better forum since there is a LG presence.
And yes to your question. Hint: Go component on it.
I have a LG 37 inch tv that I'm loosing my patience on. The problem is, almost every other day, I get an error message that says invalid format. The only way I can get the TV to come on is to turn it on and off @ 5 times. I have already replaced the HDMI cable, and it was better for a while, but now the problem has come back. I've called DirecTV, and of course, they say it's not them. Has anyone had this problem?