No audio on some recordings through web interface

I noticed this first on NBC during the Olympics. It seems like the web interface would switch between the two audio tracks randomly through the recording. Just this last week, I have noticed that at least twice, my Today show recordings are missing audio when I watch through the web interface. If I jump to the middle of the recording, I get audio, but if I jump back toward the beginning, it is gone again.

I tried playing the .mpg file directly, and there is audio on the first track (English), but no audio on the 2nd track (Spanish), so I assume that for some reason, the transcoder in the Channels DVR server is sometimes using the 2nd audio track instead of the first one.

This problem exhibits itself while watching a recording in progress, and also days after it was recorded, so it at least it is consistent when it happens.