Any idea what's going on with 2.1 and its subchannels? Sometimes signal strenth is excellent. Other times the picture keeps breaking up. Other times nothing at all. This is with a roof UHF/VHF antenna. The other channels are consistent. But on 2.1, 2.2 and 2.3 the signal is completely undependable. Are they having some kind of problem? Anybody else experience this?