--- a/toolkit/mozapps/update/nsUpdateService.js
+++ b/toolkit/mozapps/update/nsUpdateService.js
@@ -1752,18 +1752,28 @@ UpdateService.prototype = {
 /**
  * A service to manage active and past updates.
  * @constructor
  */
 function UpdateManager() {
   // Ensure the Active Update file is loaded
   var updates = this._loadXMLFileIntoArray(getUpdateFile(
                   [FILE_UPDATE_ACTIVE]));
-  if (updates.length > 0)
-    this._activeUpdate = updates[0];
+  if (updates.length > 0) {
+    // Under some edgecases such as Windows system restore the active-update.xml
+    // will contain a pending update without the status file which will return
+    // STATE_NONE. To recover from this situation clean the updates dir and
+    // rewrite the active-update.xml file without the broken update.
+    if (readStatusFile(getUpdatesDir()) == STATE_NONE) {
+      cleanUpUpdatesDir();
+      this._writeUpdatesToXMLFile([], getUpdateFile([FILE_UPDATE_ACTIVE]));
+    }
+    else
+      this._activeUpdate = updates[0];
+  }
 }
 UpdateManager.prototype = {
   /**
    * All previously downloaded and installed updates, as an array of nsIUpdate
    * objects.
    */
   _updates: null,
 

new file mode 100644
--- /dev/null
+++ b/toolkit/mozapps/update/test/unit/test_0073_update_dir_cleanup.js
@@ -0,0 +1,43 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+/* General Update Directory Cleanup Tests - Bug 601701 */
+
+function run_test() {
+  do_test_pending();
+  do_register_cleanup(end_test);
+
+  removeUpdateDirsAndFiles();
+  setUpdateChannel();
+
+  writeUpdatesToXMLFile(getLocalUpdatesXMLString(""), false);
+  var patches = getLocalPatchString(null, null, null, null, null, null,
+                                    STATE_PENDING);
+  var updates = getLocalUpdateString(patches);
+  writeUpdatesToXMLFile(getLocalUpdatesXMLString(updates), true);
+  writeVersionFile("99.9");
+
+  standardInit();
+
+  // Check that there is no activeUpdate first so the updates directory is
+  // cleaned before the remaining tests.
+  do_check_eq(gUpdateManager.activeUpdate, null);
+  do_check_eq(gUpdateManager.updateCount, 0);
+
+  var dir = getUpdatesDir();
+  dir.append("0");
+  logTestInfo("testing " + dir.path + " should exist");
+  do_check_true(dir.exists());
+
+  var versionFile = dir.clone();
+  versionFile.append(FILE_UPDATE_VERSION);
+  logTestInfo("testing " + versionFile.path + " should not exist");
+  do_check_false(versionFile.exists());
+
+  do_test_finished();
+}
+
+function end_test() {
+  cleanUp();
+}