Geckozone

Hello, i've come across a bug in Modzilla Firefox, and i have no clue how to solve it. Every now and then, especially when i'm on facebook, the whole firefox windows becomes like this:



The two pictures you see in the black area are videos from facebook posts.

What can i/you do to solve this issue?

I really like firefox so that's why i want to try and solve it rather than switching to another browser...

It's a French community forum.