we also have some trouble opening certain PDFs.
Opening those few PDFs with Firefox AND Adobe Reader PLUGIN causes the PDFs not to render correctly. I think it also happens with the Adobe Acrobat Plugin. Changing behaviour to not to open with the Plugin, instead downloading the PDF first and then opening it with Adobe Reader or Acrobat works, the PDF is rendered correctly.
The error messages are the following: "Es ist ein Grafikfehler aufgetreten" and "Nicht genügend Daten für ein Bild". Don't know the exact translation in the english version, but it should be something like: "A graphic error occured" and "Not enough data to render the picture".
Opening the PDF from a webserver directly works also as it works with Internet Explorer, because IE doesn't support the Adobe Plugins in my testing environment. So IE is downloading it first and the opening with Reader directly.
I attached a picture of the erroneous PDF in Firefox.
Thanks for your help...