Although the 612 is not the best damn receiver out there the issues you are having would not happen on 7 replacements consistently, software update is definitely needed for these but for minor buggy glitches that typically do not include what you are talking about. Get someone out there to test your system from top to bottom, replace cable, reallign dish, possibly replace a bad LNB (yes a bad LNB can affect only one receiver if multiple are connected to it) and go from there. Are the channels your having issues with HD? If so, do they both come across the same transponder? If thats the case I would turn my attention to the LNB and find the short but it could also be an issue with the electric outlet or surge protector it is plugged into.