There is another thread here about NWN Diamond's invisible robes and how if a character wears it, you cannot see his entire torso. I have the same problem and another one: I cannot see whips either. They still make the sound when attacking, but the whip itself is invisible. I tried installing the HOTU critical rebuild but the problem is still there.

The solution for the robes problem, according to the older thread, is to downgrade my Nvidia. I don't know if this will fix the whips but it's worth a shot. As I'm a complete newb when it comes to this topic, I'd like a step by step guide to doing so.

Also, for those who can confirm that this solution works, does going back to an older Nvidia version negatively affect other games?