In the past couple weeks I have noticed some of my channels are giving a gray screen with the "searching for signal" message. I went into diagnostics, and the channels with this problem are showing zero signal. My cable provider is charter. Some of the problem channel are bbca, boomerang, teen nick, and a bunch of others. I know for sure this wasn't a problem when Doctor Who was showing the last episodes of series 6, since I was able to watch them. Before I descend into the hell that is charter support, any suggestions on what may be causing the problem?