It actually isn't only the PN50a650, but also the HLS-5687W. Both will keep the video settings I put in for days, but eventually they all of a sudden lose it and go back to what the TV had default for the "movie" selection. I don't get it.

Any ideas why? There is no pattern on how long it actually takes for them to reset. Sometimes it is a few days, sometimes it is up to 30+ days.