My new HR20 HD DVR has arrived to replace the defective one originally installed. This one exhibits a new problem. Only and always on channel 87 (ABC HD West Coast feed), the audio stutters badly and adds loud & annoying pops and clicks. The audio problems are absent on my 2nd HD receiver and were absent on my first HR20. DirecTV has been stalling in helping me resolve this one, promising me calls back which never come. I have another bad HR20, don't I?