Why are my editing files locked?

Is there anyway to unlock files so I can edit them on another machine at the same time the game (not the mission) is running? I used to do this with OPF but in ArmA, when I try and save changes (from the remote machine) the files can't be saved!

Armed Assault locks those files while the game has focus. As soon as ArmA looses the focus the files will be unlocked and you should be able to edit them again.