Arma wont launch from steam but will on pw6

[brad7 4]

When i try to launch arma 2 on steam i get: "shaders not valid [mismatch of exe's and data?]".

When i try to launch arma 2 oa i get: "No entry 'C:\Program Files(86)\Steam\steamapps\common\Arma2\bin\config.cpp/CfgDifficulties/Recruit.recoilCoef" + "shaders not valid [mismatch of exe's and data?]".

I can launch the game on pw6 but i still get the errors and i want to install project reality but it says op arrowhead must be installed first so im guessing its something to do with it aswell..

Edited August 31, 2013 by brad7