FIREFOX SHUT DOWN TO SITES WITH FLASH

Which version of firefox are you using? I don't experience such crashes since firefox 3.0.

I use firefox 3.0

First be sure your system is fully updated/upgraded with no pending packages...

Open a Terminal from the menu Applications → Accessories → Terminal and type:
(when the system ask you a password give your user password, you will not see nothing when you type it, then press enter)

sudo dpkg --configure -a
sudo apt-get -f install
sudo apt-get --fix-missing install
sudo apt-get clean
sudo apt-get update
sudo apt-get upgrade
sudo apt-get dist-upgrade
sudo apt-get clean
sudo apt-get autoremove

Hope this helps

Then try to clean firefox mozilla profile

Close all opened Firefox and try to delete your Firefox user setting open a terminal from applications → Accessories → Terminal and type:
mv .mozilla .mozilla_old
and restart Firefox.

If you have a lot of bookmarks please export them before move your setting directory, then import them again from saved file into Firefox.
Also take note of your installed Firefox extensions, to reinstall them.

if this works then delete the .mozilla_old directory, from terminal, type:
rm -fr .mozilla_old

hope this helps