Index: code/mission/missiontraining.cpp
===================================================================
--- code/mission/missiontraining.cpp	(revision 6056)
+++ code/mission/missiontraining.cpp	(working copy)
@@ -853,7 +853,7 @@
 
 // Goober5000 - removes current message from the queue
 void message_training_remove_from_queue(int idx)
-{	
+{
 	Training_message_queue[idx].length = -1;
 	Training_message_queue[idx].num = -1;
 	Training_message_queue[idx].timestamp = -1;
@@ -864,8 +864,30 @@
 		Training_message_queue[idx].special_message = NULL;
 	}
 
-	for (int j=idx+1; j<Training_message_queue_count; j++)
-		Training_message_queue[j - 1] = Training_message_queue[j];
+	Assert( Training_message_queue_count < TRAINING_MESSAGE_QUEUE_MAX );
+	for (int j=idx+1; j<=Training_message_queue_count; j++) {
+		if ( j < TRAINING_MESSAGE_QUEUE_MAX ) {
+			// move all higher messages down one index
+			Training_message_queue[j - 1] = Training_message_queue[j];
+		} else if ( j == TRAINING_MESSAGE_QUEUE_MAX ) {
+			/* We are supposed to slide down the message in the last index, but
+			because it is the last index, we just need to "copy" from invalid. */
+			Training_message_queue[TRAINING_MESSAGE_QUEUE_MAX - 1].length = -1;
+			Training_message_queue[TRAINING_MESSAGE_QUEUE_MAX - 1].num = -1;
+			Training_message_queue[TRAINING_MESSAGE_QUEUE_MAX - 1].timestamp = -1;
+			// Not a memory leak because we have already moved the pointer down,
+			// so it gets deleted later when expires.
+			Training_message_queue[TRAINING_MESSAGE_QUEUE_MAX - 1].special_message = NULL;
+		} else {
+			// Somthing has majorly messed up.
+			mprintf(("message_training_remove_from_queue(int idx=%d) {\n"
+				"j = %d; Training_message_queue_count = %d; "
+				"TRAINING_MESSAGE_QUEUE_MAX = %d\n",
+				idx, j, Training_message_queue_count,
+				TRAINING_MESSAGE_QUEUE_MAX));
+			Int3();
+		}
+	}
 	Training_message_queue_count--;
 }