Channels may work great for weeks...then sound, or picture, or both will fade in and out constantly. Often, out of the blue, little squares of all different colors will fill the screen and then I get the "no signal". I may have channel 2 for weeks, and then in its place get a black screen with again the "no signal. Right now I am experiencing this with Ch 5. Sound for maybe 10 seconds-then cuts out. This is very frustrating...what might the problem be?