Originally Posted by bla
The root of the problem is that pdf is a graphical format and some pdf documents are just a series of graphic images with little or no actual text depending on how the original scan was done, this creates problems displaying on some readers that do not have a native adobe app built in.. personally I always try and avoid pdfs and convert any pdfs I do get as already suggested
PDF is not a graphical format although it can handle graphics and images, it is a layout format that was originally aimed at producing files for print output with a strong emphasis on precise typographical layout.
A number of recent PDFs don't display because the format has been changed and earlier implementations can't handle some of the latest files... I've had similar problems with some PDFs but they always open with the latest version of Adobe Reader or Acrobat... Not much help when trying to use a firmware implementation of an earlier version of the software but equally conversion can solve it as can saving from Acrobat to an earlier format.