I had a collection of files on a server that I needed to download. I could view them using the Acrobat XI pdf plug-in with no problem in Safari on the Mac. The files when downloaded could not be opened due to corruption. I could download them directly and still could not open them. How corrupt would they have been for the plug-in to allow viewing of all pages? To make a long story short, I was able to upload them from the plug-in to acrobat.com. The files not only could be viewed from within Acrobat.com with no problem, but when downloaded from acrobat.com they were now usable in Acrobat with no issues.
Sort of like washing a Word file by saving to rtf or a Frame to mif. It is worth a shot if anyone runs into a problem with a collection of files.