What OS are you using?

Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac Options) key, and then starting Firefox. Is the problem still there?

dscarborough said

Just installed Firefox today. It Runs for 15 seconds then shuts down. Have not been able to set preferences, visit web sites, nothing at all.

None of the solutions worked. But it is solved. One of the tabs that automatically started when the browser opened for the first time was bad. Mozzilla actually put up an apology screen that gave me the chance to close all tabs and open the browser without any tabs. All is well.

That's 'good to hear. Please flag your last post as Solved Problem so other will know.

What was the bad page that caused the problem?