I also tried a different hdmi cable, it's not the cable.
I have my cable box connected via HDMI, and my two component inputs are used by an xbox and nintendo Wii. While watching cable (HDMI 1), the picture went out and I got a message that there was no device connected to that input. This clearly wasn't the case. I've since tried all 3 hdmi inputs with different devices, and it always says nothing is connected to that input, and accordingly won't even let me select the input as active. My component inputs work fine. I have a hard time believing that there was some random problem with all 3 hdmi inputs at the exact same time for no reason. Any thoughts?