My first 622 was rebooting every day, and not at the correct time, just random times during the day. I ended up returning it to Dish and got a new one.
My new on has rebooted a couple of times in a few weeks. So it is much better than the old one, but still annoying. Last night we were taping two things on the sat tuners, and watching a OTA channel, and I guess it was too much for the 622, it spontaneously rebooted itself.
Annoying as hell, but better than my old 622. I am not sure if it is a hardware flaw, or something that can be fixed with a future update, but I am hoping the latter.