Save functionality no longer works

The plugin still works, but new boxes and overrides no longer. When hitting save I always get: Warning: array_key_exists() [function.array-key-exists]: The second argument should be either an array or an object in wp-content\plugins\more-fields\more-plugins\more-plugins-admin.php on line 303

http://wordpress.org/plugins/more-fields/