Thanks, Vincent, for your advice.
I just tried exporting it as an AVI instead of a DV AVI, and the plain AVI is a smaller file and has worse visual quality. That’s exactly contrary to your advice. Hmmmm. What’s going on here? The DV AVI file size is 5.4 GBs, and the AVI is 4.1 GBs.
BUT…
When the plain AVI is burned onto a DVD as video (MPEG2), the stills behave just as they do in my Premiere sequence.
So to recap:
DV AVI (looks better, bigger file size)
Premiere sequence: Stills are fine
Playback when exported: Stills are fine
Burned to DVD: Stills are all #@*#%& screwed up!
AVI (looks worse, smaller file size)
Premiere sequence: Stills are fine
Playback when exported: Stills are fine
Burned to DVD: Stills are fine