Index: backup/util/structure/backup_optigroup.class.php
===================================================================
RCS file: /cvsroot/moodle/moodle/backup/util/structure/backup_optigroup.class.php,v
retrieving revision 1.1
diff -u -r1.1 backup_optigroup.class.php
--- backup/util/structure/backup_optigroup.class.php	21 Apr 2010 09:17:10 -0000	1.1
+++ backup/util/structure/backup_optigroup.class.php	1 Nov 2010 14:34:11 -0000
@@ -46,7 +46,7 @@
 
     public function add_child($element) {
         if (!($element instanceof backup_optigroup_element)) { // parameter must be backup_optigroup_element
-            if (!$found = get_class($element)) {
+            if (is_string($element) || !$found = get_class($element)) {
                 $found = 'non object';
             }
             throw new base_optigroup_exception('optigroup_element_incorrect', $found);
Index: backup/util/xml/simpletest/testwriter.php
===================================================================
RCS file: /cvsroot/moodle/moodle/backup/util/xml/simpletest/testwriter.php,v
retrieving revision 1.1
diff -u -r1.1 testwriter.php
--- backup/util/xml/simpletest/testwriter.php	21 Apr 2010 09:17:11 -0000	1.1
+++ backup/util/xml/simpletest/testwriter.php	1 Nov 2010 14:34:11 -0000
@@ -303,6 +303,9 @@
         $xw->stop();
         $result = $xo->get_allcontents();
         $fcontents = file_get_contents($CFG->dirroot . '/backup/util/xml/simpletest/fixtures/test1.xml');
+        
+         // Normailse carriage return characters.  
+        $fcontents = preg_replace('/\r\n/', "\n", $fcontents );
         $this->assertEqual(trim($result), trim($fcontents));
     }
 }