go to terminal
$ sudo rmmod psmouse
$ sudo modprobe psmouse proto=imps
if proto=imps doesnt work, try proto=exps
try the touchpad again for scrolling..
if it works, u need to make it permanent.
$ sudo vim /etc/modprobe.d/options
options psmouse proto=imps
reboot PC.
credits here (http://ubuntuforums.org/showpost.php?p=9207727&postcount=2)