Superficially it looks as though you might be trying to view a PDF file without a pdf viewer (Acrobat).
All files have an extension - the file name then dot and then the extension - like this....
Mendit.pdf
The extension tells you the sort of application programme that can make use of the file - you do not mention the extension of your troublesome files - it's important that you should know.
Good luck..., November 2014
