:: Thanks Sam, I got that overall impression ;) Unhappily I am not keen to install Acrobat, so I will hack around the issues as best I can.

Some PDF viewers are not following the PDF specification (which is still authored by Adobe) too well (in part because of the lack of methods for validation in ISO 32000-1), Adobe Acrobat is the benchmark to assess the validity of a PDF file. PDF remains de facto a proprietary format, not an open standard, even after the 1/07/2008 evolution (I am a Foxit fan myself BTW).