Encountered a very strange problem with my Tivo HD last night. All of a sudden, all the menu screens because completely jumbled - picture jumping with horizontal lines and a lot of green color mixed in. I can see the cursor moving around when I use the remote, but I can't really see what's going on. If I switch to live TV, everything is fine. If I switch from HDMI to composite (haven't tried component yet), the menus work. What would cause the menus to be bad but tv to be fine?