go into a console and
su in with your root password.
Type
Code:
vi /etc/X11/XF86Config
Substituting
vi with which ever editor you use, then scroll down to the device input section for your mouse and add this line:
Code:
Options "ZAxisMapping" "4 5"
Then save the changes and restart X or reboot. Your mouse wheel should now work. Although, strangely enough, it should work with the same config :/
This is the only thing I can think of right now... sorry.