Hello. Twice now I've managed to get a TiVo HD into a mode where no video displays. When I say no video, I mean no video. The menus appear but the background light bulbs video is missing -- just black screen. The unit continues recording, but you can't play any videos and live TV is just blank. It's as if everything is working except MPEG playback. This doesn't happen spontaneously, but I'm unsure of the sequence that causes it. A reboot cures it. Running the latest (c) system. Anyone else seen this? Thanks.