Recently upgraded to Firefox 33.1. I have been using Firefox as my primary browser for the last few years. After installling v33.1, I will be browsing, Firefox will freeze, my screen will go white, and then my screen goes black essentially shutting down my computer. It has happened about 2 time a day. I do not receive an error message. I patiently waited (about 5 minutes before it completely makes my computer inoperable) and the computer or browser does not "unfreeze." Not good. I am not on my computer often (as I have a full time job), but it causes problems when I am in the middle of researching and writing a graduate school paper! Gah! I just ran the update for 33.1, so hopefully that will fix the issue.