That's happened for years. IF you leave it tuned to an OTA station that might have signal drops, it can cause the receiver to reboot. Just make sure that if you watch an OTA channel, that before you leave to go back to a satellite channel, you park it on your strongest station.
I have never had that happen, but I am getting a reboot on both my 722k's when I try to do a rescan, so I can't get the channels that have changed freqs.
Was it right after you exited Youtube directly from a video, to return to the regular UI? I've seen that on my Tivo once in a great while, and discovered it doesn't happen if I EXIT the video I'm watching first, and am on the default Youtube menu before exiting.
It was while watching a Youtube video. The screen would go black and the Hopper would not respond to any buttons an then reboot.
It would then start up on the last satellite channel watched before going to Youtube.
Yes, my 722k with module is rebooting about 2 times a week when left on a OTA channel. The channel is very strong and this has been happening for about 2-3 months.