Can you post your 'xorg.conf' ? It should be something like:
Code:
Section "InputDevice"
Driver "mouse"
Option "Protocol" "auto"
Option "Device" "/dev/input/mice"
Option "ZAxisMapping" "4 5"
EndSection
If that doesn't work try the 'evdev' driver, read 'man evdev' or see here:
http://gentoo-wiki.com/HOWTO_Advanced_Mouse