I was editing the prefs.js and users.js files to eliminate all the Babylon entries and when I reloaded Firefox, suddenly the "Welcome to Firefox" tab kept appearing. Here is what I found: Open the user.js file in your profile folder with a text editor. Look for this entry: user_pref("browser.startup.homepage_override.mstone", "rv:8.0"); Change the numbers (in this case) "8.0" to the current revision of Firefox. ie: 9.0.1 (current version when this was written ). So it should look like this: user_pref("browser.startup.homepage_override.mstone", "rv:9.0.1"); Save the file and restart Firefox. The same line also appears in the file "prefs.js". Make sure that one is correct also if you are still having problems. In my case, it is was already correct. Hope this helps.