Yes, it is a driver issue. Also, they said that there was going to be another patch to The Witcher 2 for some kind of lag issue with the mouse on Windows 7. There is already a patch from Microsoft about said mouse lag for the main OS functions, but not for games.
here is link for patch 1.2 news which should come out tomorrow.
http://www.en.thewitcher.com/community/entry/50/
Looking @ this makes me feel old...PROUD owner of NES, SNES, GENESIS, TurboGrafx 16 (PCE), N64, PSOne, PS2, Dreamcast, Xbox360, and PC.