Basically when you have more than one GPU rendering graphics, and enable HDR the screen flickers from light to dark while moving your character making the game unplayable.
Anyway that thread had gone long and unsolved and I gave up and since the problem was only on my laptop (with SLI 8800M GTX) I hadn't bothered much and played the game on my desktop on the 8800GT.
I was thinking the problem was Nvidia-SLI related but when I upgraded my desktop 8800GT to a 5970 (single card with 2 graphics processing unit) I found that now I got the problem on the desktop as well!
So, since I didn't find anything using the search function, during my absence has any solution been found to this bug? I'm pretty sure it isn't something the graphic card vendors should fix - it persisted on both my nvidia cards and my amd card no matter how many drivers I tried out...