Yeah, that was my first thought, but when I reloaded the project it was not muted. Two thoughts come to my mind on this note:
One, if a sound track is muted (especially if it is the only audio track), it would be a good idea for PD to give a warning before rendering, a la "Warning: This video production has no active audio track! Render anyways?". And two, if the audio track(s) is/are muted, they should also be muted in the preview so that it would tip off the user.
I never was able to pin down the culprit, but what made it a little unusual was that it actually rendered an audio track - it was just totally silent (VLC media player showed that that there actually was an audio stream - Tools/Media Information menu).
Anyway, it's only happened this one time. Maybe it was just a fluke. Of course I'll report back if it happens again.
Russell1967
System specs: Windows 7 Professional x64; Gigabyte Z77-DS3H motherboard with i5-3579K 3.8Ghz processor with 32GB RAM; Zotac GTX 760 w/4GB; 1xWestern Digital 1TB 10,000RPM HD; 1x Samsung 840 Pro SSD System Drive