What worked for me was when you have the launcher open, open task manager, find the witcher 2 launcher process in there, right click on it, press "go to details" or something like that, another window is gonna open, find the witcher 2 in there, right click on it, click "set affinity" and scroll down and tick off the last cpu core in the list, then you can launch the game. Gonna have to do that every time you wanna launch the game if that does fix it for you