having the exact same issue, and have tracked down that there is no files in my Documents folder, the ArmA3 folder does not exist. Another strange issue I noticed was when I attempted to use Six launcher to launch the game through steam, the program recognized an error: "It appears your game Key is not entered into the registry"

The methods I've tried so far include:

--using -winxp and -nobenchmark
--I do not use ZoneAlarm, but I checked my anti-virus and it wasn't at fault.
--updated DirectX through the provided launcher
--Ran steam in admin mode and without, reinstalled several times