Comment 3 for bug 446611

I notice the same behaviour running nvidia 185 driver with compiz enabled in Opera web browser. Scrolling further down the page to clear the gap off the screen and returning back to the same spot seems make the blank area disappear. I've also had X lock on occasion when I scroll quickly down a page. Sometimes X recovers, other times it locks up hard and I have to alt+sysrq+K to restart it.