I have no idea what I did nor how. I am running Window 7 32-bit with 4GB of RAM on the machine in question.
Files will open normally, but when I have the viewer pane active and highlight a .pdf file on my PC, I get prompted as if I am trying to download a file from the internet.
A popup window with the title "File Download" opens with the question, "Do you want to open or save this file?" I can download another copy of the file from my PC to my PC or I can click on "open" and it will open it within Adobe Acrobat (not within the viewer pane).
The viewer seems to understand .docx, .xlsb, .zip, and most other files. Somehow I must have set something to interpret .pdf files as internet files. For example, for a file name "REVIEW_GUIDE.pdf" the heading on the viewer pane will say "REVIEW_GUIDE.pdf (Internet Explorer)" with the message "Navigation to the webpage was canceled" in the viewer panel itself.
I cannot figure out how to return the behavior back to how it worked before and works on my other machine which display the .pdf contents in the viewer panel (it seems to refer to Adobe pdf for Vista 32-bit in the heading, but I am not sure what this machine used to say). Did I somehow delete or inactivate a viewer plugin?
Thank you for any help you can provide to get me back on track. Even a page reference in the manual would help.