Index: modules/system/system.admin.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.admin.inc,v
retrieving revision 1.77
diff -u -r1.77 system.admin.inc
--- modules/system/system.admin.inc	25 Jun 2008 09:12:25 -0000	1.77
+++ modules/system/system.admin.inc	27 Jun 2008 21:45:20 -0000
@@ -619,6 +619,13 @@
   }
   $dependencies = array();
 
+  // Remove hidden modules from display list.
+  foreach ($files as $filename => $file) {
+    if (!empty($file->info['hidden'])) {
+      unset($files[$filename]);
+    }
+  }
+
   // Store module list for validation callback.
   $form['validation_modules'] = array('#type' => 'value', '#value' => $files);