My olivea tv will just lose picture. I'll hear a kind of high pitch squeal and then static. After a few seconds, the screen comes back. It shows no signal in the bottom left hand corner and 4.0 in the upper right. When I turn to channel 4, the picture is back. Then, it may do it again, and I have to repeat the process. Once I get the screen back, all I have to do is hit channel 4 and comes back. I dont know if its the tv or the cable box. Why does it keep doing this? Its almost like its losing channel 4.