Same woes for me...
I have the same issue and agree that this is a signal strength issue. After three installers came out (the last one said that this was a known issue that they had received a memo on from DISH), I still have the same problem. The problem is only on local HD channels. In my area, Atlanta, the local HD channels appear on satellite 129 transponder 4. My signal strength is 48 to 52 on the meter. I have a 722 DVR. The installer told me that he can not improve the signal strength. After escalating to a supervisor at DISH, I was told that the signal strength was too low and that was causing my problem. I told the final installer this and he said the signal could not be improved and that there was nothing he could do. I have been left with two options, live with it or change service providers. I will be changing.