Mozilla Firefox - re-initializing the plugins database

In some cases, you may not be able to install or re-install a plugin. Re-initializing the plugins database may fix this problem:

1. Open your profile folder:
   
   1. At the top of the Firefox windowOn the menu bar, click on the Help menu and select Troubleshooting Information. The Troubleshooting Information tab will open. At the top of the Firefox window, click on the Firefox button, go over to the Help menu (on Windows XP, click on the Help menu)On the menu bar, click on the Help menuAt the top of the Firefox window, click on the Help menu
   2. Under the Application Basics section, click on Open Containing FolderShow in Finder. A window with your profile files will open.folder
      Note: If you are unable to open or use Fire​fox, follow the instructions in Finding your profile without opening Firefox.
2. At the top of the Firefox window, click on the Firefox button (File menu in Windows XP) and then click ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select QuitAt the top of the Firefox window, click on the File menu and select ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select Quit.
3. Delete the pluginreg.dat file.
4. Open Firefox
5. In the Location bar type about:plugins and press Enter to bring up the Firefox plugins list. Return

Mozilla Firefox - re-initializing the plugins database