Please check if all your plugins are up-to-date. To do this, go to the Mozilla Plugin Check site.

Once you're there, the site will check if all your plugins have the latest versions. If you see plugins in the list that have a yellow Update button or a red Update now button, please update these immediately.

To do so, please click each red or yellow button. Then you should see a site that allows you to download the latest version. Double-click the downloaded file to start the installation and follow the steps mentioned in the installation procedure.

All are up to date

For the adobe a very good solution is this http://kb.mozillazine.org/Flash#Disabling_Protected_Mode_in_Flash_11.3 Disabling Protected Mode in Flash 11.3

You can disable Protected Mode in Flash 11.3 and above by adding the line ProtectedMode=0 to the Flash "mms.cfg" file located in:

   (Windows 32bit) C:\Windows\System32\Macromed\Flash 
   (Windows 64bit) C:\Windows\SysWOW64\Macromed\Flash 

For example, on a Windows 7 64-bit system, open the C:\Windows\SysWOW64\Macromed\Flash folder, copy the file "mms.cfg" to the desktop, open it in Notepad, add a new line ProtectedMode=0 and then close Notepad, saving your changes. Next, go back to the C:\Windows\SysWOW64\Macromed\Flash folder, rename the original file to "mms.cfgBAK" (to save it as a backup) and then drag and drop in the modified "mms.cfg" file from the desktop. [42] [43] [44] [45] [46] [47] [48]

Note: To re-enable Flash Protected Mode, either restore a backup of the original mms.cfg file, if you saved one, or else re-edit the mms.cfg file to remove the ProtectedMode=0 line you added. Updating Flash Player or installing a newer version does not automatically re-enable Protected Mode. [49] [50]

But the problem with pdf I don't find a solution.

Hello,

In order to change the default reader for PDF files (to not open PDF files with Firefox's internal PDF reader), follow these steps:

1. Go to Tools > Options (or Firefox > Options).
2. In the Options window, select the Applications tab.
3. In the Search field, type PDF. You should find Portable Document Format (PDF).
4. On the right handside you should find an Action column. Use that to select your favorite PDF reader. In order to view PDF files in Firefox, choose Preview in Firefox.

Did this fix your problems? Please report back to us!

Thank you.

I follow your step and now the firefox show me a black page and loading the pdf. I wait about 5 minutes but it still loading . I want for ex to view a brochure from a shop no more than 30-50 mb and i have fiber conexion 100 mb. Other ideas?

And I receive an error a small window name ENU message is " ! Adobe pdf document" and I have only option "OK"

Hello,

Certain Firefox problems can be solved by performing a Clean reinstall. This means you remove Firefox program files and then reinstall Firefox. Please follow these steps:

Note: You might want to print these steps or view them in another browser.

1. Download the latest Desktop version of Firefox from http://www.mozilla.org and save the setup file to your computer.
2. After the download finishes, close all Firefox windows (click Exit from the Firefox or File menu).
3. Delete the Firefox installation folder, which is located in one of these locations, by default:
   • Windows:
     • C:\Program Files\Mozilla Firefox
     • C:\Program Files (x86)\Mozilla Firefox
   • Mac: Delete Firefox from the Applications folder.
   • Linux: If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see Install Firefox on Linux. If you downloaded and installed the binary package from the Firefox download page, simply remove the folder firefox in your home directory.
4. Now, go ahead and reinstall Firefox:
   1. Double-click the downloaded installation file and go through the steps of the installation wizard.
   2. Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.

Please report back to see if this helped you!

Thank you.