I have just upgraded from a direct tv with tivo unit to the HR 21 for HD. So far it is ok. Couple of things I miss. I had a few questions that maybe someone could address. First I have my bedroom TV hooked up thru HDMI from the HR-21 to back of the TV. It is an LG LCD. I notice that on some of the HD channels the audio will disappear but on the same SD channel it will have audio. Is this an HDMI problem. If I change channels and then come back to that HD channel the volume is fine or if I turn TV on then off again. I could hook the DVR up thru component or optical audio if needed. Second what is the USB port on the front of the unit for. Is it only for hard drive expansion or can it be used for something else. Could it be used to plug a USB adapter to get it on a network? My last question is there a way to switch between the 2 tuners on the DVR. Like if you are recording a show and watching another I used to be able to press the down button on the remote and switch to the recorded show.