This is a known incompatibility between late versions of Adobe Acrobat Reader and Firefox. Here is what to do about it:
First you have to make sure you have Adobe Reader version X running. By the way, the X stands for the Roman numeral 10. As of this writing Adobe Reader’s most current version is 10.0.1. You find the version number by opening Adobe Reader, clicking Help, About Adobe Reader. The version number is in the bottom left corner of the About window.
If you are on anything older than Acrobat Reader version 10 you should first download the latest version from a safe and fast download location for Adobe Reader like this one here. After the download you have to run the downloaded installer (or setup) program.
After the installation is done you have to do a simple setting in Firefox to avoid problems. In Firefox:
- Click Tools, Options, Applications.
- In the Options window:
– Find all entries for “Adobe Acrobat…” with a PDF icon (below marked red).
For every entry:
– on the right side click on the entry and then on the drop down arrow (below marked blue)
– and select “Use Adobe Reader (default)”, below marked pink.
- Click OK and all should be fine.
The Options window should look like this: