@domel: I have this problem on QVC Plus, b/c that's not in HD. (I have Optimum cable). There's an easy remedy. Press the # key at the bottom right of the numbers pad, and it will give you two other picture resolution options. Then, when you change the channel back to an HD station, press the # again to go back to the original resolution. This might not work for all cable providers. Hope this helps.
~~Be careful when you follow the masses. Sometimes the 'm' is silent.~~