I don't have the definitive answer to this (not having PS/2 hardware for a long time now), but I would start by having a look at /var/log/Xorg.0.log for any mouse-related errors
Code:
grep -i mouse /var/log/Xorg.0.log
It may be that the X-server needs to fall back to legacy drivers to support your mouse. The Xorg config files are located in /etc/X11/xorg.conf.d/, and specifically 60-layout.conf may need this entry
Code:
Option "AllowEmptyInput" "false"
which forces X-server to support input devices that require the 'mouse' and 'kbd' drivers.
Some possbily useful references:
Input device configuration - FedoraProject
HAL, xserver 1.5.3 and AllowEmptyInput « Motho ke motho ka botho
Some googling may be necessary...
Bookmarks