Why my Magnazox dvd recorder looses preprogrammed channels

I have a Magnavox model zc352mw8a dvd recorder 120vac. I can program the channels into it off of an antenna. The channels are there but then I can power the unit off then back on and maintain the programmed channels. But if I power the unit off for a period of a hour or more it looses the channels. They are no batteries in this unit for cmos for it is a cabinet mount player.