The best feature of Firefox is the support for 1000s of Add-ons to increase the features. Sometimes Firefox fails to start up because of some add-ons. When Firefox is opened, it runs in background and it is present under the processes list in task manager but is not listed under applications that are running. This is a common problem with Firefox and the solution is also simple.
1. First go to Task Manager and end process “firefox.exe”.
2. Go to programs -> Mozilla Firefox -> Firefox (safe mode)
3. In the check list select for defaults and disable all add-ons.
4. Click make the changes and restart.
Now Firefox will start normally without any issues.