Problem with the media.php file

Hi.

The last couple of days I get this message, when I try to edit a uploaded picture:

Fatal error: Call to undefined function add_shortcode() in /hsphere/local/home/baltzer79/littlepinknotebook.dk/wp-admin/media.php on line 715

I’ve tried to disable all the plugins and have tried to change the theme to Twenty Eleven and nothing happens ??

It doesnt affect the frontend of the site, luckily, but it’s annoying as h*ll and the support team from my webhost is trying to help, but they cant figure out what to do, so I’m turning to you guys…please help me ??

/**
	 * Process the [embed] shortcode.
	 *
	 * Since the [embed] shortcode needs to be run earlier than other shortcodes,
	 * this function removes all existing shortcodes, registers the [embed] shortcode,
	 * calls {@link do_shortcode()}, and then re-registers the old shortcodes.
	 *
	 * @uses $shortcode_tags
	 * @uses remove_all_shortcodes()
	 * @uses add_shortcode()
	 * @uses do_shortcode()
	 *
	 * @param string $content Content to parse
	 * @return string Content with shortcode parsed
	 */
	function run_shortcode( $content ) {
		global $shortcode_tags;

		// Back up current registered shortcodes and clear them all out
		$orig_shortcode_tags = $shortcode_tags;
		remove_all_shortcodes();

		add_shortcode( 'embed', array(&$this, 'shortcode') );

		// Do the shortcode (only the [embed] one is registered)
		$content = do_shortcode( $content );

		// Put the original shortcodes back
		$shortcode_tags = $orig_shortcode_tags;

		return $content;
	}

Thanks
Tina