Sometimes when I scroll in firefox, I will a block of the same content from another portion of the page rendered where it shouldn't be, almost like the browser didn't scroll properly.
I suspect that this has something to do with my video driver, and some stability issues I've been experiencing. I'm using the recommended driver, 280.13.
Thanks to a comment above, I was able to figure out that I only had these scrolling issues when I was scrolling over a flash element in a web page.
It seems to be fixed now. I followed the instructions here: https://askubuntu.com/a/29776/36361
And then ran: