Well I have been having issues with errors that state "The instruction at 0x00000000 referenced memory at 0x000000000 The memory could not be written", there is also a case where it will say "memory could not be read" for others.
A quick Fix for what seemed to work for me was to reinstall Arma 2 from scratch. Make sure you delete all files and folders on your hard Drive that pertain to Arma 2 also. After that do a clean install of Arma 2 , Arma 2 OA and the DLC. Make sure when the games are installed to run them separately to make sure all DLC is installed. After everything has ran, make sure to validate the game cache thru steam. Launch OA and then make sure all expansions are selected and loaded to OA. Do the same with whatever launcher you are using. Delete the mods and then reinstall. This should help with the errors but success is not guaranteed.
Another way that this error happens is from other programs that are conflicting with the arma files. Ex Adobe. To be able to narrow it down a clean boot is the easiest way to determine what is causing it. A clean boot will let you choose what programs are running at that specific time. Google clean boot instructions and follow the directions. Its easier to read those than to explain them here.
Good Luck!!!
