Try to delete the mimeTypes.rdf file in the Firefox Profile Folder to reset all file actions. *http://kb.mozillazine.org/mimeTypes.rdf *http://kb.mozillazine.org/File_types_and_download_actions#Resetting_download_actions You can also try to delete the pluginreg.dat file and the addons.sqlite database file. You can use this button to go to the Firefox profile folder: *Help > Troubleshooting Information > Profile Directory: Open Containing Folder ---- Create a new profile as a test to check if your current profile is causing the problems. See "Basic Troubleshooting: Make a new profile": *https://support.mozilla.org/kb/Basic+Troubleshooting#w_8-make-a-new-profile There may be extensions and plugins installed by default in a new profile, so check that in "Tools > Add-ons > Extensions & Plugins" in case there are still problems. If the new profile works then you can transfer some files from the old profile to that new profile, but be careful not to copy corrupted files. See: *http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox