Backup and restore

Hello,
I am unable to backup any of my courses in Moodle 1.9. The backup hangs with the following error:

Name:	backup-infection_control-20080108-0554.zip
Creating temporary structures Deleting old data Creating XML file Writing header Writing general info Writing course data Course info Blocks Fatal error: Call to undefined method block_participants::backup_encode_absolute_links_in_config() in C:\Program Files\xampp\htdocs\moodle1-9\backup\backuplib.php on line 966

I don't know whether it's related, but on the highest error reporting setting on, my front page is riddled with these warnings above some of the blocks (with no adverse effects to their function).

Notice: Undefined property: object::$specific in C:\Program Files\xampp\htdocs\moodle1-9\blocks\moodleblock.class.php on line 688

Is it a bug, or do you think I've broken something?