The cable guy showed up (early!) today and figured out what was wrong and fixed it in under 20 minutes.
He had only one question for me:"When did you first get cable."
I was a bit surprised and told him 9 years ago. He then nodded his head and told me he now had a very good idea about what was going on. I probably had a video trap on my line and all he had to do was pull it off. Apparently it was installed when we first got cable and has now given up the ghost. We just have basic cable and the trap was installed to filter out the unwanted (to us) premium channels.
I'm not sure if he installed a new one, it might not even be necessary at the point. I just hope I don't get stuck in the same situation as this person.