For some reason, TWC has had continuing problems with Fox's HD network signal since they went "HD" in early September. KRIV upconverts all their local material (blue sidebars) to 720p. The network is also 720p, but something in that signal stream...sometimes even when there is no HD program (black sidebars) has caused on-going problems at TWC. They've "fixed" it several times, but eventually, some piece of equipment goes down or is rebooted...and it obviously doesn't hold it's configuration.
Right now...if you watch the network signal for several minutes, depending upon the amount of action and "datapoints", you'll see picture shifts, pixelation (especially during dissolves or very fast motion), and all manner of problems. TWC is supposed to be hunting down the culprit once again. And...the problems are different depending upon which set top box you have. It seems that the 6200 is their "problem child" at this point. Obviously, it's not a problem on most channels, and I suspect that the problem has something to do with the PSIP data in the digital stream.