I am getting the same problem. The Error 25: dvdvideo_spec_violation.
However I can not simply "not use" chapters.
Its correct that when I create chapters - the error occurs. If I remove chapters everything works fine. Tried on multiple projects, different sizes, etc. Same results.
The problem did not start occuring until I upgraded from Nero 6 to Nero 7.
I had Nero 6 Ultra and everything seemed to work fine. Then I upgraded to Nero 7 Ultra and its been weeks with no resolution. Same system, only difference is Nero 7.
Any ideas -