Welcome to Giant Bomb!  
 
On topic, I have no idea how to fix this.  I just wanted to welcome you to the site.

Dont know how to fix it and welcome to the cult called giantbomb.

In case anyone's wondering, the exe file you need is "witcher2.exe" within the "bin" folder in the game directory.  
 
I wasn't having this problem myself, but I'm using Force Alternate Frame Rendering 2 (I think) for my SLi setup, which seems to perform better than the default. 

After downloading the Nvidia_Inspector tool and messing with a Witcher 2 profile SLI setting I got those weird lights. I put the profile back to default and they went away.

Just to update: I've also reset my profile settings to default after patching the game. It runs buttery smooth now, and performance is merely dependent on the game's config settings, rather than needing any messing around with nVidia profiles. 

I get something similar in a crossfire setup.

@scarace360:  cult?  what you say willis. this isnt a cult. this is a forum where we troll each other and we pretend that we arent trolling by flaming and trolling other trolls.   damn willis, you crazy :D

i'll see once i get that game...should be pretty soon after i beat some of my other games :P