AutoDesk Smoke :: Unable To Export Sequence / Work

Having cut together a short commercial recently, I have been unable to export my sequence/ work.  There are no error messages, only incomplete exported versions of the sequence (sometimes 1 second, sometimes 8 seconds!) or nothing at all.  It will go through the motions and not generate an exported file.
 
I have attempted to export my sequence multiple ways - from the timeline, from the media library and from the mediahub - with identical results.  I'm totally at a loss.  I've also gone back to a sequence which I was able to export successfully one month ago and now I get the same problem - either no result or some fractional piece of the edit - never more than a few seconds.  My finished edit, by the way, is a 30-second spot.
 
For example, here's one way I've attempted to export:
 
1.  I select my sequence from the media library and right-click for export.  
2.  I select movie, choose my destination, and select a format preset (I've tried just about every preset, hoping it was a preset error of some kind), and
3.  I hit export.  
 
Instead of the spinning prompt in the lower left corner, showing me a percentage countdown (or count-up) - which was present a month ago when I was las exporting a show -I get a quick audio mixdown prompt in the lower left then nothing.  It all happens in less than 1 second from the time I press "export".
 
I've copied the console log for your review.  This particular effort/ screenshot resulted in an 8-second clip, which is the longest one (still incomplete) I've been able to generate since I attempted to export starting yesterday.  Again, my sequence is 30 seconds, and it either does nothing, generates an empty file (45k in size) or creates an incomplete movie file (usually 1 or 2 seconds).