I've been pissed off many times by the fact that the scrolling on my touchpad just stops working all of a sudden. I couldn't figure out what was causing it to stop working. Sometimes it would just start working again on it's own and other times I would just reboot my machine to fix it.
Well, other people have discovered that watching online flash videos in full screen mode is what triggers the problem. And the weirdest thing is that it can be fixed by hitting the spacebar twice!! Is that bizarre or what. Software!! It really makes you wonder.