Hello, The appeal Restore Firefox can solve many problems, restoring Firefox to its default state, saving your critical information. Note : This will make you lose all extensions and some preferences. Open sites will not be saved in Firefox 25 and lower versions. To Restore Firefox do the following: Go to the Firefox menu> Help> Data to Support. Click the "Reset Firefox" button. Firefox will close and restart. When Firefox is ready, a window with the imported information will be displayed. Click Finish. Firefox will open up with all the factory default applied. For more information from the article Restore Firefox - easily correct most problems . If the problem persists after restoring Firefox (which is not the same thing as reinstalling Firefox), it is likely that the problem is due to a Malware, as described above. I hope this information is useful! Please let us know if this solves your problem. Thank you,