Our 921 has been showing this problem with increasing frequency: while playing back a recording, the audio & video will freeze up. The only way to start it up again is to hit fast forward and play again, which will cause it to play after a few seconds delay. Some of the characteristics I've noticed are: 1. The freeze is reproducible if we back up to the same point in the recording. 2. It occurs with with both satellite and OTA recordings, as well as live TV we've buffered up by pausing. 3. On a few occasions I've heard a distinct clunk from the hard drive, which makes me a bit nervous that this might be a progressive hardware failure. 4. We're currently at L2.73 and the problem has been getting much worse, though I saw this at the previous software release as well. This is starting to drive me nuts, since it's now typically occurring 2-3 times per hour of playback. Has anyone else seen this behaviour? Any idea if this is a hardware problem that I need to get a replacement from Dish for, or is this a problem with the recent software releases?