Thanks for coming back to me.
OK, I think I have solved the problem....
I am using Dual Layer discs 2h-10mins and I notice that the auto (switch layer) in Encore was in use. As a last attempt I decided to use manual switch layer and it now burns and works fine !!
I can only assume that Encore puts a hidden chapter mark at a point within the timeline and this therefore causes problems with my own chapters?
Once I used manual switch layer mode it was fine.
However, if I bring into Encore footgae that has not been transcoded then there is never a problem, apart from poorer quality ? The above problem only happened when I brought in Mpeg2 transcoded footage!!
Up to now I have been importing HDV footage and letting Encore transcode it (auto mode) for me but I must admit it does not do a great job regarding quality and seems to use more space?
If I first transcode in Premiere HDV to Mpeg2 then it looks much better and takes up less space !! I just have to remember from now on to manual set layer switch mode!