Batman

So.. I havent played Arma3 for around 2 days.. I decided to play it today with some friends and when i try to join any server it tells me im using modified data file. I can't see the opfor, blufor selection screen.. Well i can see the UI but not the teams/ words etc. I can click "OK" and it will start loading (when i click "OK" i can see the opfor, blufor teams/ words etc) When it loads it gives me a blank box with only one option "CLOSE" This closes my connection with the server and im back on the server list screen. I haven't touched any of the files.. and if I had... I have reinstalled the game 2 times.. deleted the files in my documents. I have even installed it on my SSD and i still have the same problem. I can play in the editor and the showcase. Any help is appreciated. Thanks. edit nevermind... i remember i put it on the Dev Build on steam.