In order to resolve this problem, you will need to edit your /etc/X11/XF86Config-4 file.
An appropriate section for a ps/2 intellimouse style device would look something like:
Code:
Section "InputDevice"
Identifier "Mouse0"
Driver "mouse"
Option "Protocol" "IMPS/2"
Option "Device" "/dev/psaux"
Option "ZAxisMapping" "4 5"
Option "SampleRate" "100"
EndSection