I've apparently solved my problem. I uninstalled Firefox 3.6.6 keeping all customizations, then reinstalled it. When it first opened, it gave me a screen saying it was embarrassed that it couldn't restore my web pages, but it gave me an option to begin a new session. When I did that, it opened normally and seems now to be operating properly.

Seemed to be oerating normally is a good choice ow words. I too though the safe mode, plus not restoring session would solve my problem, but then opening certain tabs --I wan't really able to experiment much before a crash, but I thought may sign-in or automatic sign-in ones--it would crash again. I really like and miss Firefox, and wish I knew haow to revert back to the previous version before it automatically udated to Firefox 4...

Like other´s I upgraded to firefox 4 and really regret this as there does not seem an answer to the problem. Mcafee protection allows full access for Firefox and it worked fine before. Now like other´s I get a brief glimpse of the browser and then the carsh report. Come on someone give us a solution or you will loose a lot of customers and I miss using Firefox.