Unable to launch combined ops after steam update

[lancemate 0]

So I logged onto steam this morning and went to run DayZ, only for steam to tell me that it needed to update the game files to a new more efficient format.

Now I am unable to launch OA: Combined Ops (note that I can launch Arma 2 and I can launch OA without combined ops)

I have tried the following

• Restarted PC.
  
• Deleted everything from steam folder except steam.exe and \SteamApps to let it rebuild my library.
  
• Downloaded BEClient.dll and BEServer.dll from BattleEye website and put them in A2OA\Expansion\BattleEye folder.
  
• Deleted and re-installed OA.
  
• Verified integrity of local game cache several times, (Always says 1 file failed verification and will be downloaded.)
  
• Right clicked OA and chosen to re-install BE with and without the launch parameters in the options. (Sometimes I get an error about missing string!!!!)
  
• Made sure no files in steam directory were read only.
  
• Tried adding steam.exe and ArmA2OA.exe to not get checked by DEP, but it says they cannot be added to exceptions and must be checked by DEP.
  

If anyone can shed any light or suggest anything else I'd be very grateful as I'm at my wits end with it :-(

[z3n 12]

Got the same problem after the update. Googled for an hour but noone seems to have a fix for it. Its not only Arma its many other games. Im not launching it from steam anymore I use Dayz Commander with launch options in that program.

[lancemate 0]

Launching _runA2CO.cmd from OA folder also works I've discovered.

Stupid steam!