Comment 11 for bug 612591

@pierre: I have a HP EliteBook 8530p, here is an easy way to apply this fix (just run those commands in a terminal):

sudo apt-get install dkms
wget https://bugs.launchpad.net/ubuntu/+source/linux/+bug/582809/+attachment/1675262/+files/psmouse-2.6.35-22-generic-patched.tar.bz2
tar -xjf psmouse-2.6.35-22-generic-patched.tar.bz2
sudo cp -r psmouse-2.6.35-22-generic /usr/src/
sudo dkms add -m psmouse -v 2.6.35-22-generic
sudo dkms build -m psmouse -v 2.6.35-22-generic
sudo dkms install -m psmouse -v 2.6.35-22-generic

And reboot.
(if you don't want to reboot, you can just try "sudo rmmod psmouse && sudo modprobe psmouse")

Please confirm if this work.