I know it is not that it does not see a HDMI signal because I can see the picture for about 2 to 3 seconds then it swithes. Also, I did a test and set the TV on the AV1 input and then turn everything off. Then when I turned everthing on the TV switched to the next input which was HDMI. I also did the same thing putting the TV on Antenna before shutting everything off and when I turned everything back on it switched to AV1. So, my feeling is it is toggling to the next input not matter which one I am on. I did change the order of start up, so that the TV was last thinking the same thing you were, but it did not seem to help.

When I select the input source on either the original TV remote or the DirectTv remote it just moves to the next input source that is senses. From HDMI it goes to antenna (again even though I technically not using it, no signal), from antenna it goes to AV1 and then from AV1 back to HDMI. I cannot just select which input I want.