I've seen this posted before, but I don't recall what the outcome was. You might call the cable company up to see if there's a reset or an update to address this issue (since the box is freaking out, and not the television, it likely points to a box issue).

You certainly shouldn't have to unplug the cable every time you turn off the TV, but if the update or reset doesn't work, you may want to see if they can switch out your box.

I don't think it's the television, but I have no way of definitively assuring you of that - but that's what I'd do.