The Error message got no impact on your game, I've had this pop up several times without losing items. I believe the error message comes from Arma 2 having a minor issue with the mod because some weapons is removed/Edited out from the game. (I'm NO tech expert). I've lost a few items due to other buggs, switching Servers after eating meat didn't register. Sometime when I had 3 Bullets left in my clip and it disappeared and sometimes my clip where full on next login. Placing a Item in a Bag without enough space would destroy an item.