I recently bought a new 46" Sony KDL46Z4100 HD TV and had DISH network install an HD DVR receiver for it and an SD TV and a separate SD receiver for another SD TV. I don't normally use external speakers. Ever since day one about 4 months ago, the sound goes out for about 30 seconds and then comes back or if I change channels, the new channel will have sound and then I change back to the original channel and it now has sound. This seems to happen only on HD channels and mostly on the Sony HDTV. Also, sometimes, the voice is not in sync with the video on both TVs running off of the HD Tuner. At first, I thought it was the Sony TV so I took it back and got a new one. I changed the HDMI cable between the TV and the tuner and tried different HDMI imputs on the TV. DISH has replaced everything except the newly installed cable (inspected it and said it was OK) and I get a strong signal. DISH has replaced the receiver twice. I am still having the same problem about once or more a day and it is really frustrating. The picture is great but once in awhile, there is also severe pixilation. The last technician who checked it out didn't have an answer other than trying composite cables instead of HDMI cables but I want to use the HDMI cable and feel the sound should work with it. Awhile back, I was watching the CMA show and the sound went out just on that show on all TVs for about 45 minutes. I called the local station to see if the problem was with them but they never called back. Any suggestions?