I'm using steam and i just bought the game today. Downloaded, ran steam as admin on the first start up of Arma II and Operation arrowhead. The game runs fine by it self, but whenever i try to connect to a dayz server, both from the server list in the game itself or Dyaz commander, it crashes like what the original poster described. For dayz i just downloaded the mod from the button thats on the home site. I dont know if i have to put it in a different folder or what, but ive finally decided to buy arma mainly based on dayz and im upset it wont work now :( any help to solve this problem for me and anyone else would be greatly appreciated!