Why you need to know:
It is not uncommon for browsers to crash when opened, but it could be one of many reasons; if Firefox crashes when you try to watch a video it could be that the Adobe Flash Player or video player installed requires an update, but if it crashes when you try to open a new tab, settings, bookmarks and/or favourites the problem is being caused by a corrupted profile or missing extensions. Pay keen attention to the pop-up error messages if there are any, these will sometimes hint on the necessary fixes as well.
What you will need:
How to get it done:
The following fix will assist in solving the crashes as it relates to corrupted Firefox Profiles or missing extensions. At the outset of crashes, it is recommended to use the virus and malware-protection software installed or any other computer maintenance program to scan the system for any viruses or errors that may have interfered with Firefox files. If you have important bookmarks saved, you may want to back up the files. Open the 'Control Panel'; if Windows XP is running on the computer, select 'Add/Remove Programs'; on Windows 7 and 8 computers choose 'Programs and Features' and find Firefox (Mozilla Firefox) and uninstall.
On Apple computers (MacBook series), go to the Finder and choose the Applications folders and drag/drop the program in the trash can - this should remove all the files associated with Mozilla Firefox for Apple computers. However, on Windows systems you will have to select 'My Computer' or 'Local Disk (C:)' and select 'Program Files' to ensure that the Mozilla Firefox applications folder is removed. This folder contains all the Firefox browser files, including the profile, extensions, settings and bookmarks folder.
Now it is time for reinstallation, you may choose to restart the computer though it is not necessary since a message box will appear after the application is reinstalled prompting you to restart to complete the process. Visit http://www.mozilla.org/en-US/firefox/new/?from=sfx&uid=288842&t=562 to download the latest version of the application. You can modify the browser settings to your preference and load back the bookmarks once installation is complete.