[https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode Start Firefox in Safe Mode] {web link} by holding down the '''<Shift> ''(Mac=Options)''''' key, and then starting Firefox. A small dialog should appear. Click '''Start In Safe Mode''' (not Refresh). Type '''about:config'''<enter> in the address bar. If a warning screen comes up, press the '''Be Careful''' button. At the top of the screen is a search bar. Type '''browser.startup.homepage''' What is the value? Right-click and select '''Reset''' to restore its default value; '''about:home''' -------------------- If there is still a problem, You may have corrupt '''sessionstore''' file(s). Delete all '''sessionstore*''' files and the '''sessionstore-backups''' folder. Type '''about:support'''<enter> in the address bar. Under the page logo on the left side, you will see '''Application Basics. ''' Under this find '''Profile Folder. ''' To its right press the button '''Show Folder. ''' This will open your file browser to the current Firefox profile. Now '''Close Firefox. ''' Locate the above file. Then rename or delete it. Restart Firefox.