Yeah i get this too, unfortunatly i dont know the cure. I have tried adjusting vidoe settings and setting them to default, nothing works. The flush thing dosnt work either, no box appears to type you just type it then the screen goes black for a short time but the polygons are still there when it returns. The polygons seem to originate from the tents. Iv also encountered then from a rusty jeep along the coast. Its unfortunate that they are so bad in brenzino since that was one of my favourite places but now i cant see 10 feet in front of me. Guess i'll just have to stay away from brenzino untill this is fixed.
