Audio Problems. When I have a comcast/motorola cable box connected thru the component inputs the

Question

When I have a comcast/motorola cable box connected thru the component inputs the sound will intermittently either sound scrambled/garbled or has a loud tone. This problem also occurs with a dvd connected in the component inputs too. Also if you select 720p or 1080I in the service menu on the motorola box there is a loud popping sound thru the tv speakers even if the audio input cables are disconnected. It seems the popping is from the Y input. If you switch the resolution to 480i or 480p it seems to go away. Any ideas where the problem is?