These situations arise when you have a later version of Adobe Reader co-existing with an older version of Adobe Acrobat Professional. In the case of Adobe Reader 9 and Adobe Acrobat 7.0 Professional, when clicking a web link to a PDF file, an error message pops up.
"The file is damaged and could not be repaired."
There are certain ways to tackle the situation; the easiest way regardless what web browser you are using is in the following link,
Working with PDF Web links.
