I have an XL4 and Comcast cable. My TiVo was acting strangely today--I got no video, just a black screen, for live TV as well as recorded shows. I still had picture--that is, I got the TiVo menus, show info, progress bar at the bottom. Anything TiVo generated was fine, anything off the cable was all black. This even happened for old shows that had been good. I rebooted the TiVo, and that resolved the issue. I'm left wondering, is this a symptom of something I should attend to, or just one of those 'sometimes you gotta reboot' things? Any of you folks see this behavior?