RCA TV swiching channels by itself

I have an RCA 35" TV Model F35665. I have it connected to a cable box which must remain on channel 3. While watching TV it will begin switching from channel to channel during this time the remote does not work. Eventually it will stay on one particular channel at which time the remote works and then I can switch it back to channel 3 in order to watch cable only to have it happen all over again. I've unpluged it for several days, when I replug it works fine for a couple of days. Has anyone experienced this same problem? Does anyone have any ideas on what is causing this? Any input is appreciated.