Since I got the 627 update, I've had a problem a few times with a blank (black with no sound) screen when I turn on the box. Sometimes I can see a live tuner via PIP, but I can't swap tuners. I can bring up the guide and the dvr recording list. I can start a recording and watch the program, but after a short time the screen goes black again. A soft reboot seem too fix the problem, at least temporarily.
I have seen the same.... yesterday, both tuners were black and no sound, even with PIP. I as able to watch recorded programs, but nothing live. It was recording at the time and the recording was black as well. Once I rebooted, it was fine...