Jim - This is what I already tried - exported using MPEG-DVD preset entitled "PAL High Quality", Main Concept MPEG Video, 720x576, 25fps.  Render/export produced m2v and wav files for each sequence, but Encore won't use them in a PAL DVD claiming they have an unacceptable aspect ratio.

REK

Jim, That was a reasonable guess, but I double checked that the Encore project was set up as a PAL project expecting to output 720x576, 25fps to a DVD.  But here is a more careful look at the error message:

         PCC "Untitled Timeline" has an error at 437.6400s

         The aspect ratio of this file is not supported by DVD

         PGC Info: name=Untitled Timeline, ref=Bpgc, time=437.6400s

Now that time is the first frame of the second sequence I put on the timeline, or rather the second m2v and wav files exported from the second sequence in Premiere CS5. Apparently the first sequence is swallowed OK, but the second is causing a problem.  All three exports were done with the same MPEG-DVD/PAL HQ preset, and all three m2v files are listed in Windows Explorer as 720x576 videos, and all three m3v files play in Windows Media Player looking the same (a wide screen video letterboxed with black bars at top and bottom).

However, if I look at the three sequences on the monitor in Encore, the first sequence has very narrow black bars on left and right, while the other two are widescreen aspect ratio surrounded on all four sides by wide black bars.

I re-exported the second sequence from Premiere with no change in result.

Anyone have an idea what's happening, or at least how I can get the PAL disk burned?

OK, Jim's advice did the trick.  I put each m2v and wav on its own timeline in Encore, changed the button references on the main menu and the project burned successfully.  Unfortunately, I don't have PAL equipment to test the disk, but all signs are positive.

To exactimage, I realized from the beginning that the 16:9 Bluray frames would get chopped or black boxed in conversion to SD PAL, but that was OK.  This was an informal effort to show a fellow who helped me shoot footage in Africa what he'd worked on - a real one-off.

I also have done many Encore projects in which I put several short video pieces on a single Encore timeline and treated them as disconnected chapters in the menu structure.  Like exactimage, I have had bothersome hesitations when I wanted one "chapter" (or video file) to feed directly into another "chapter" (or video file), but not this breakdown in recognizing file properties.  Guess I've learned a good lesson.  THanks, especially Jim.