Due to a recent Adobe Reader update, many people are having trouble viewing PDF files in a browser (Firefox, Internet Explorer, etc.). Please try the following steps to troubleshoot the problem:
Go to "Start" -> "All Programs" (or "Programs") -> "Adobe Reader" .
You may get a message asking whether you want to disable Protected Mode
Select "Always open with Protected Mode disabled" if you know that the PDFs that you work with normally come from a trusted source.
Select "Open with Protected Mode disabled" if you want to be asked every time when you view a PDF.
Go to "Edit" -> "Preferences..." and make sure "Enable Protected Mode at Startup" is NOT checked
Close your browser (Firefox, Internet Explorer, etc.) and make sure that no session is hidden or open.
Restart your browser and go to the website where you download the PDF and try to view it again.
The issue is normally resolved at this point, if not, please try the following instruction:
Close your browser and make sure that no session is hidden or open
In Adobe Reader, go to "Edit" -> "Preferences..." and click "Internet" in the "Categories" column on the left side, then on the right side, in the "Web Browser Options" section, make sure that "Display PDF in browser" is NOT checked, and then click "OK" to confirm the change.
Please note: if both Adobe Reader and Adobe Acrobat Pro are installed in your computer. You may see that "Display PDF in browser" option is greyed out in the Adobe Reader's Preferences. This is due to the setting in Adobe Acrobat Pro. If this is the case, please open Adobe Acrobat and go to "Edit" -> "Preferences..." -> "Internet" to edit the setting there.