Success with "exporting" depends somewhat on the content and makeup of the .fla file.
For example, the actionscript doesn't get exported... basically all you get when you export is an image of a frame.... so straight frame by frame animations can export pretty well.
Also review the export settings and export at the very highest quality, uncompressed settings.
If you are just producing a slideshow, using a real video editing program like Premiere will give better, quicker results... no exporting, then import and then author to DVD, etc. Just create in Premiere and author.... done!
Best of luck on this one.