Hey guys
while I was trying to fix the random crashes and lag issues I was getting whilst playing the game, I discovered that the installation of the witcher 2 wasn't particuarly clean. I have never seen such fragmentation caused by a game install, so after reinstalling the game I defragged my drive. So far the game is running like a dream, if it worked for me it may work for others. BTW I have XP.

P.S I had installed the patch before I discovered this.