I have a Panasonic TH-50px75u that is making a hissing noise. It's coming from the tv and only happens when there is video on the screen. Another thing I noticed is that the noise varies depending on which mode the tv is in. It's the loudest in Vivid mode, a little softer in normal, and at its softest when in Cinema mode. I can still hear it in Cinema, but it's really irritating when you're watching a movie or tv show and you have a couple of people talking softly because my soundbar doesn't drown out the noise. Anyone know why this is happening and where exactly the noise could be coming from?