I had this problem but found a fix (customer service was no help). I used the parental controls and blocked all the QVC channels. My TV hasn't switched since. I never purchase from them so it's no issue for me. I hope this helps someone else with this aggravating issue.
Thank you! Have had this issue for months! Customer service does not know what to do! We even switched to a new box and it is doing the same thing! Will try your idea! Thanks! So glad someone else had the same issue!!! Thanks for posting!