Thanks for looking into this.
So, the suggestion is that this issue is unique to my machine? Puzzling. I am running all the Adobe CS6 video applications, Final Cut X, Motion, Compressor, etc, as well as the usual assortment of still image software and have no issues. The same clips show up as thumbs in everything else, including Aperture 3, Lightroom 4 and even Capture One 6.