Thanks to all for your responses. I've been trying to isolate the issue, and have mixed results.
First, I have burned (with a lot of work) a 25 clip, 25 chapter, 24 transition blu-ray. I haven't tried again with the full 26 clips.
I sliced and diced my original project, creating other, smaller projects from the original. I finally got it to a three-clip, three-chapter, two transitions track that consistently fails to burn, getting the motionmenugeneratior error message. The first transition was "glass2." I created a copy project (save as) from the bad one, removed glass2, and it consistently burns. Or replaced glass2 with pagecurl and it burns. This points strongly to glass2, right?
But no. I replaced glass2 with pagecurl in the big original and it fails. I replaced all transitions with fade and it fails. And here's where it gets weird.
I noticed that the clip that followed where glass2 had been was jerky. If I played the clip it was not jerky, but if i played the movie and positioned the timeline pointer into the prior clip (so that it moved thru the fade/transition) then the next clip was jerky. I thought maybe something in the prior clip was affecting the jerky one, so I trimmed one second from it.
And it worked. The jerky clip was no longer jerky. I tried to burn this fixed movie, and it failed, but much deeper into the project. I found a second jerky clip, changed its transition and trimmed the prior clip, and then the whole movie burned.
All of the clips are 1440x1080, 29.97 framerate clips. As for using SVRT, it is greyed out. I found a post that said Canon HF100 can't use SVRT for some reason. Bummer. I might post a second question about hardware rendering when ATI stream is enabled, but I'm trying to keep the issues posted clean.
The perceptive among you will notice that my earlier post said 26 chapter, and I'm now saying 25. This was in the interest of marital harmony. The missing clip is of my wife saying "that thing isn't on, is it?" to the camcorder that is on (but the Grand Canyon in the background is, indeed, Grand). But in the interest of this experiment I'll try again with the full 26 when I have time.
23 days left. Yes, this is a rewritable BD.
REM