Zenith TV Source Sense - Broken?

I was wondering if anyone else has encountered this problem with Zenith TV's and whether there is a menu based fix. My Zenith D32D51, circa 2001, has a Source Sense feature - the TV can determine what cables have been plugged in (Composite, S-Video, etc.) and cycle through only these inputs when I press the Source button on the remote.

My problem is that the TV insists the coaxial cable (what the TV refers to as the "Antenna" source) is plugged in when it clearly is not. The onscreen menu thinks that it is plugged in. And when I cycle through the sources, one of the inputs is the Antenna input, which is nothing but static. But the coaxial cable is clearly no where near the television.

Has anyone else seen a "ghost" source on a Zenith TV? Is the problem mechanical/electrical or some obscure option on the menu system that I missed?

This is really bugging me, so thanks much for your help!