On my daughter's TV, I've noticed, about once every other month or so, the resolution of the DVR (HR22) keeps reverting back to 480P and I have to re-select 1080i and 1080p and de-select 480P. There is no way she would have any idea at all to change the resolution, so the DVR is doing it on its own. Has anyone else run across this issue? Any known causes? Native is set to "off".