Index: simplemenu.module
===================================================================
--- simplemenu.module	(revision 5362)
+++ simplemenu.module	(working copy)
@@ -187,6 +187,17 @@
   }
 }
 
+/** \brief The cache is being cleared.
+ *
+ * Simplemenu uses a cache which, when being cleared, needs to be rebuilt.
+ * This means we want to delete the CSS filename info since that file is
+ * being deleted at that time.
+ */
+function boost_flush_caches() {
+  variable_del('simplemenu_css_filename');
+}
+
+
 /** \brief Add the module theme.
  *
  * This function adds a theme for the Simplemenu look.