Hi!
Put it in your "monobook.js", and it will work.
uncaught exception: [Exception... "Node was not found" code: "8" nsresult: "0x80530008 (NS_ERROR_DOM_NOT_FOUND_ERR)" location: "http://commons.wikimedia.org/w/index.php?title=MediaWiki:ImageBoxes.js&a... Line: 84"]
in Mozilla/5.0 (Windows; U; Windows NT 6.0; cs; rv:1.8.1.4) Gecko/20070515 Firefox/2.0.0.4
-- [[cs:User:Mormegil | Petr Kadlec]]