This has been happening since forever when I bought my Premiere two years ago. I assumed it was some limitation in the Flash environment, that they couldn't switch to/from Live TV vs HD Tivo menu (with video preview window) without losing the audio stream. But now that we have full-screen Guide (since Fall update?) it doesn't lose audio going to/from that seemingly identical HD screen. Do others experience this same issue, and has Tivo ever addressed it?