Turns out of you do a search on the forum for 'heap zone', you'll find that this is a recurring problems, and that there is no one solutions. Sometimes re-starting works, most often doesn't. Ditto reparinig permissions. Ditto making sure no special characters are in the titles.
What's happened, according to an Apple Specialist I called, is that something got 'corrupted' -- a 1 changed to a 0, or vice versa; and his advice was, if re-starting doing clear it, then totally re-make the half hour project!
What I did with the half hour movie was this:
-Duplicated the movie twice.
-Deletedthe last half of the first dup, and the first half of the second dup.
-Exported both halves independ of each other-- each exported with no 'heap zone' problems.
-Then inported the two exports, put them back together, finalized them by Sharing with the Media Browser, then when that was fininished, evoked iDVD.
I do suggest continuing to report this problem to Apple.