May be you can analyse the structure of the DVD using IfoEdit ?
I'm not familiar with that? Will have a look
Chapters are a misconception.
DVD consist of Domains, TitleSets, Titles, PGCs, PGs and Cells (top to bottom structure). Chapters are in fact only pointer markings optionally attached to PGs. The transitions between structural blocks get larger with higher structural level. E.G on PGC level it's almost like starting a new presentation, e.g. audio and video needs to be completely restarted. May be this were the VDR dvd-plugin has it's problems to play some structural transitions seemless.
May be you can post a copy of the .IFO files on the questionable disc and I can give you some hints or advices (I work with DVD software profecionally and have access to all the specs and tools neccessary).
kind regards Peter
Thanks Peter - I have posted the files from a problematic DVD :
http://home.comcast.net/~nzbaxters/video_ts.ifo http://home.comcast.net/~nzbaxters/vts_01_0.ifo http://home.comcast.net/~nzbaxters/vts_02_0.ifo http://home.comcast.net/~nzbaxters/vts_03_0.ifo http://home.comcast.net/~nzbaxters/vts_04_0.ifo