Chapter Playlist play order bug?

I like the idea of chapter lists. It will make things much easier than rendering
out lots of separate clips and bringing them in as separate timelimes.
But, I have struck one problem in experimentaion someone might like to comment
on.
I set up a test project of 12 short films with separate play buttons for each
clip and I thought I could use a chapter playlist to Play All. What I found is
that I could not add all the chapters to the list in sequential order (1 to 12).
As soon as I try to preview, Encore throws up a number of "internal
software error" dialoge boxes. If I put just one chapter out of order it
will preview ok!
I have recreated the problem in a fresh project with 5 chapters. Here there are
no unnecessary end actions or such and as simple as otherwise possible.

Postscript