When changing HD channels through Comcast cable box I briefly lose the picture when broadcast resolution changes from channels (720 to 1080). When using the pass thru on my Yamaha amp the picture will not return at all. The cable box has to be turned off then back on. I have checked everything, all settings, HDMI cables, and inputs and replaced the cable box. I even sent the amp back to Yamaha for testing. They could not duplicate the problem. Comcast says I have excellent signal strength. This is a new amp, about 6 months old. It worked fine when it was first hooked up.