How funny, I started having a similar problem last night. I've had my TivoHD for a few days now and still awaiting cable cards, so I have it set up for analog cable and OTA. It's been running fine, but then last night, watching live TV caused it to hang and stutter. The UI was functional as I could change channels and access all the menus. Watching recorded shows was fine too. It was just live TV that didn't work. I know it's not a cable problem because my TV could tune into those channels fine. I did a reset of my Tivo HD and the problem went away.