Hi Lopo,
You should try to not use a profile in Nhancer/driver Nvidia ; Just tweak it in general tab. Don't sure if it will fix it but why not try ?
I had problems with last Nvidia drivers and profile tweak so it's why i say you that.
I have a 8800GTS with 169.44 and i don't have the flat sun. And don't need the flat fix. And i don't use Adaptive AA at all ..
OLC : Your GUI seems to work OK in 1680/1050
I just have to understand to use it.