Are you unable to use Firefox at the moment ? Reinstalling Firefox will not solve the problem, because it tries to retain settings, but take care, you are in danger of loosing bookmarks and history if you are not careful. The problem is easier to sort out with Firefox running. Do NOT use any delete settings option when uninstalling , not sure how it is worded - (at least until the profile has been successfully copied somewhere safe) '''First step''' is to try starting firefox in [[safe mode]] but initially do not change any of the listed settings in the first window dialogue, just click the continue button.