I have a 50" RCA Projection TV. I just recently hooked it up to digital cable, and for the past week, I can hear this high pitched humming type noise. I have no idea what the problem could be. Has anyone out there ever experienced such a thing? And if so, how can I fix it??? I have checked the cable to see that it is secure, and it is, I can hear the noise, even when the tv is on mute,- I'm not sure if that helps or not. Thank you very much in advance for your input!