This is a very common problem with NWN, I've found.
Try re-downloading the haks once more. Occasionally they become corrupted. As well, update any drivers his video card has - this is the most common cause of the problem,for whatever reason.
Also, is he running Vista? If so, make sure to run the game on Administrator mode - right click on the shortcut, 'run as administrator.' For whatever reason, Vista likes to block random things for absolutely no reason unless the person using the computer has top-secret CIA clearance (admin mode.)