Jill watches TV using an antenna over the roof. Leo says that's the best quality HDTV because it isn't compressed. Suddenly, however, channel 2 (2.1) is missing on her TVs, while her mom still has them. Leo says that Jill is likely on an edge area where it can work, but may not work at other times. She should check out TVFool.com and it will tell her what channels are available in her area. One TV may have a more sensitive tuner than the other, or it could be that less cable is also used, minimizing attenuation. It may just be that the antenna has shifted a little bit, so she should try and repoint it. A better antenna can help as well. It could also be her cables. There's all kinds of things that could impact it.
The chatroom says that there is a known issue with over the air broadcasts with CBS in LA right now.