diff -Naur asterisk-1.6.2.8-rc1-orig/apps/app_meetme.c asterisk-1.6.2.8-rc1/apps/app_meetme.c
--- asterisk-1.6.2.8-rc1-orig/apps/app_meetme.c	2010-04-02 19:56:45.000000000 -0400
+++ asterisk-1.6.2.8-rc1/apps/app_meetme.c	2010-05-25 15:11:27.000000000 -0400
@@ -1713,12 +1713,14 @@
 {
 	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, 
@@ -3352,7 +3354,9 @@
 			}
 		}
 		/* 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) {