yea, it seams to be problem only in Vista 64
but as you, i reinstalled my vista, so i cant find which updates was installed in last couple months.
we need to find which update is in colision with that updated Gameguard and uninstall it (if its possible, some isnt)

this is actally bad way, i dont want to uninstall any system updates, but im not going to buy new system because of game and i dont think thay will fix it ..
so we need to get list of last updates first and then try to uninstall one by one, and find whichone is in colision.
if you find that, plese let me know