system
13
Type “about:config” in address bar
promise to be careful
scroll down to “browser.startup.homepage_override.buildID;20140314220517”. Right click on it and select “reset”.
scroll down one below to “browser.startup.homepage_override.mstone;28.0” and do the same thing.
Close then reopen Firefox. You’ll see 2 tabs appear the 1st time, but that should be it…
When you reset these strings, you will need to modify your preferences again within Firefox (such as your homepage).