Why wont firefox let me use facebook?

[Emily]

I was having a problem with Firefox a few days ago where if I tried doing anything on any website, suddenly Firefox would stop responding. I would exit out of the browser, pull it back up and go to the website, it would work for a few seconds and then just stop responding again. After scanning my computer, deleting and re-downloading Firefox, de-fragmenting my computer and updating flash player, now other websites I use work just fine except for Facebook.

I can log into Facebook and -sometimes- I am able to go on another Facebook page but after that, Firefox stops responding and I have to use the task manager to get out of it.

Does anybody know what I can do to fix this?