Munin API submodules define new paths via Munin API, so they need to clear menu.

modules/munin_apc/munin_apc.install

@@ -0,0 +1,18 @@
+<?php
+/**
+ * @file
+ * Drupal APC instrumentation for Munin: installation.
+ *
+ * @author Frederic G. MARAND
+ *
+ * @copyright (c) 2011 Ouest Systèmes Informatiques
+ *
+ * Licensed under the General Public License version 2 or later.
+ */
+
+/**
+ * Implements hook_install().
+ */
+function munin_apc_install() {
+  variable_set('menu_rebuild_needed', TRUE);
+}

modules/munin_core/munin_core.install

@@ -0,0 +1,18 @@
+<?php
+/**
+ * @file
+ * Core Drupal instrumentation for  Munin: installation.
+ *
+ * @author Frederic G. MARAND
+ *
+ * @copyright (c) 2011 Ouest Systèmes Informatiques
+ *
+ * Licensed under the General Public License version 2 or later.
+ */
+
+/**
+ * Implements hook_install().
+ */
+function munin_core_install() {
+  variable_set('menu_rebuild_needed', TRUE);
+}