I hooked my newly purchased surroundbar 4000 to my LG flatscreen using the cables and wires provided wit the surroundbar. After about 10 minutes of use the sound becomes distorted by a loud, digital chirping sound. If I turn off the soundbar and turn it on again the chirping stops but then usually starts again 10 minutes later. This is the 3rd surroundbar 4000 that I have purchased (returned the other 2 for this same reason). Any ideas why this could be happening?