Had the same problem too, even reinstalled everything, just didn't check out if the problem still occurs, but for now I can say, that I never had this before installing patch 1.55. I will come back later and tell you if the reinstall solved it.
I found out, that this did not happen, when lowering the graphic options and/or not setting the view distance to like 3500-4000 m. I wasn't testing if it may occur some time later then it did when view distance was at 4000m.
Besides that I did not notice any other problems so far, but I haven't played more than like 1 hour since updating the game due to the game freezing when closing the map...was too annoying :P
My system:
mainboard: ASUS P5E Deluxe
CPU: Intel Core 2 Quad 9550 (OC)
RAM: 8GB Corsair
graphics adapter: ATI Radeon HD 4870
sound: Creative SB X-Fi Xtreme Gamer
(drivers all up to date)
edit:
so I checked it after reinstalling my OS and ArmA2+OA+patch 1.55 and experienced the same problem. But only on Warfare maps on Chernarus and not, when setting view distance lower than 4000 m, which actually sucks, 'cause my system definetely usually was able to do like 6000-7000 m. This still works on Domination-map on Takistan. There I had no problems with that and graphics. Besides yesterday I also had objects that suddenly disappeared and came up again.
Well, as long as this won't be fixed it's impossible to have the gaming experience I had before patch 1.55.