My mouse works perfectly in X except for when I try to run a game
which uses fullscreen mode. The mouse freezes and stays in the top
left corner of the screen.

I am currently running Gentoo Linux
I have a Logitech MouseMan Optical mouse
I am also using the newest nvidia-kernel supplied by gentoo's portage
My /etc/X11/XF86Config is:

Driver "mouse"
Option "Protocol" "IMPS/2"
Option "Device" "/dev/psaux"
Option "ZAxisMapping" "4 5"

Any help would be greatly appreciated. Have spent an age tryig to find
info on this but couldnt find anything relevant.