Index: source/simulation2/system/TurnManager.cpp
===================================================================
--- source/simulation2/system/TurnManager.cpp
+++ source/simulation2/system/TurnManager.cpp
@@ -214,10 +214,16 @@
 	if (m_CurrentTurn >= turn)
 	{
 		// The most likely explanation is that an observer that's lagging behind is sending commands,
-		// which is possible when cheats are enabled. Report & ignore.
-		// It seems a bad idea to error out too badly here:
+		// which is possible when cheats are enabled (this allows coop-play).
+		// It seems like it could be desirable in the future for observers to message other observers,
+		// so it will be ignored then. If the target is a real player, warn about it.
+		// @see CNetServer::OnSimulationCommand for additional details.
+		if (player == -1)
+			return;
+
+		// Report & ignore. It seems a bad idea to error out too badly here:
 		// nefarious clients could try and send broken commands to DOS.
-		LOGWARNING("Received command for invalid turn %i (current turn is %i)", turn, m_CurrentTurn);
+		LOGWARNING("Received command for player %i on invalid turn %i (current turn is %i)", player, turn, m_CurrentTurn);
 		return;
 	}