Fixing Firefox when it F's up

http://kb.mozillazine.org/Browser_will_not_start_up

How to make Firefox/Mozilla Suite start

1. Completely close the application (using "File -> Exit") and make sure Firefox is not running in the backround.
2. Firefox only. Run Firefox in safe mode. If it starts up in safe mode, the problem is most probably with one of your themes or extensions. Select the default theme in "Tools -> Themes" and disable all your extensions in "Tools -> Extensions". Restart Firefox.
3. Before continuing, be sure to back up your profile.
4. Delete "XUL.mfl" (the name may differ slightly, e.g. "xul.mfasl") from your profile folder. This file will be regenerated on next startup. Try running Firefox now.
5. Delete "chrome" and "extensions" folders from your profile. (You will lose all your extensions and themes!)
6. Delete the "Cache" folder. (You will lose your cache.)
7. If application still does not work, it is usually best to create a new profile.
8. If it still doesn't work, try reinstalling the application. Remember to uninstall the application first.


What do I do if my profile's corrupted?

If your profile is corrupted, try creating a new profile. If it's still acting weird, then try uninstalling and reinstalling the application.

Assuming it works with a clean profile, you can copy the following files from the old profile into the new one. (Note, that some of these files may not exist.)

* bookmarks.html
* cookies.txt
* hostperm.1
* user.js
* chrome/userContent.css
* chrome/userChrome.css
* Any other files that you need