As far as I can tell, everything is default. Downloaded directly from Steam. All I did was finish installing DayZ, load the game, Alt+E, choose map, start messing around until I get that error when setting a unit.
Here's a screencap. This error appears while trying to add a unit in the editor. Google returns 0 results for this error, which makes me think I'm doing something completely wrong. I've verified the integrity for everything Arma related, still no luck. Any clue what's going on? EDIT: Also, why is the text cutoff on the right side?