--- asterisk-1.4.31/apps/app_meetme.c	2010-02-22 13:52:34.000000000 +0000
+++ asterisk-1.4.31.meetme-fix/apps/app_meetme.c	2010-05-24 23:04:25.000000000 +0100
@@ -1313,17 +1313,21 @@
 	return 0;
 }
 
-static void conf_queue_dtmf(const struct ast_conference *conf,
+static void conf_queue_dtmf(struct ast_conference *conf,
 	const struct ast_conf_user *sender, struct ast_frame *f)
 {
 	struct ast_conf_user *user;
 
+   	ast_mutex_lock(&conf->playlock);
+
 	AST_LIST_TRAVERSE(&conf->userlist, user, list) {
 		if (user == sender)
 			continue;
 		if (ast_write(user->chan, f) < 0)
 			ast_log(LOG_WARNING, "Error writing frame to channel %s\n", user->chan->name);
 	}
+
+   	ast_mutex_unlock(&conf->playlock);
 }
 
 static void sla_queue_event_full(enum sla_event_type type, 
@@ -2487,9 +2491,14 @@
 			if (confflags & CONFFLAG_MARKEDUSER) 
 				conf->markedusers--;
 		}
+
 		/* Remove ourselves from the list */
+	   	ast_mutex_lock(&conf->playlock);
+
 		AST_LIST_REMOVE(&conf->userlist, user, list);
 
+	   	ast_mutex_unlock(&conf->playlock);
+
 		/* Change any states */
 		if (!conf->users)
 			ast_device_state_changed("meetme:%s", conf->confno);