Comment 7 for bug 288937

I have the same issue with a Latitude D630. Rolling back the Nvidia driver also worked for me.

One other thing to note: After booting with the newer graphics driver and getting the fan cranked up, rebooting, even to a different operating system (Win XP) wouldn't reset the fan. Had to shut all the way down and then start back up before the fan would ever start responding to changes in actual operating temperature again.