Here's a run-down of the problems I experienced in the week or so that I had my first HR21 DIRECTV box:

  1. Blank recordings (black/empty screen)

  2. Recordings that do not play (ask “delete?” when played)

  3. Recordings with video and audio drop-outs, unwatchable

  4. DVR stops responding to Remote and Front Panel Buttons

  5. Black screen “Not authorized - Searching for signal” on certain channels

  6. Fast forward speed 4 freezes and stops fast forwarding

  7. Gets stuck doing a “search by title”, finally times-out and returns to “live TV”

It's only been 5 days, but so far (knock on wood), I have not seen these issues yet with the second HR21, although I have not really had an opportunity to test items 5 and 7.