Aperently the disapearing mouse cursor so many of us expirience is NVIDIA driver bug !!!!
The bug introduce itself in ALL 8x.xx version drivers .
So far 2 temporal solutions exists :
1. Install v7x.xx drivers.
or
2. Right click on desktop, go to "Properties" , "Settings" tab , hit "Advenced" button, "Troublesot" tab there , then change the
"Hardware acceleration" slider from "Full" one step down.
This will prevent problem from happening but will reduce you Windows and most importent gaming performance.
(As a side not if you manage somehow to reach there using keyboard it will restore the cursor even after it disappeared).
More descussions on the issue is here : http://www.techsupportforum.com/other/75719-mouse-pointer-keeps-disappearing.html
and here : http://forums.nvidia.com/lofiversion/index.php?t9572.html
