Is this a new installation of Firefox or did you upgrade from an earlier version? ''If it is a new installation,'' please see these articles: [https://support.mozilla.com/en-US/kb/Images%20or%20animations%20do%20not%20show Images or animations do not show]; [http://support.mozilla.com/en-US/kb/Firefox%20cannot%20load%20websites%20but%20other%20programs%20can Firefox cannot load websites but other programs can]. ''If it was an upgrade,'' something may have gone wrong in the process. You might want to create a new Firefox profile and then selectively transfer you bookmarks and old settings to the new profile. First, I recommend backing up your Firefox settings in case something goes wrong. See [https://support.mozilla.com/en-US/kb/Backing+up+your+information Backing up your information]. (You can copy your entire Firefox profile folder somewhere outside of the Mozilla folder.) Next, fire up the Profile Manager and create a new blank profile: [https://support.mozilla.com/kb/Managing+profiles Managing profiles]. If the new profile works, you can move key settings like bookmarks from your damaged profile to the new profile: [https://support.mozilla.com/en-US/kb/Recovering+important+data+from+an+old+profile Recovering important data from an old profile]. Hope this helps.