I also went to System | Preferences | Mouse then the new Touchpad tab: the vertical scrolling box was checked. I tried unchecking it, and scrolling still did not work; I went back to the Mouse preferences and re-enabled the vertical scrolling, but scrolling still did not work.
I also went to System | Preferences | Mouse then the new Touchpad tab: the vertical scrolling box was checked. I tried unchecking it, and scrolling still did not work; I went back to the Mouse preferences and re-enabled the vertical scrolling, but scrolling still did not work.