DOM 8 Exception

Hey Guys,

after the first install of the plugin everything worked quite good. But since then, i added some new plugins and did some changes on my theme, including the functions.php, syntaxhighlighter throws an Dom 8 Expetion on the line
document.getElementsByTagName("head")[0].insertBefore( corecss, document.getElementById("syntaxhighlighteranchor") );

But the syntaxhighlighteranchor is in the head section. So i really dont understand, why it isn’t working.

Here’s the page, where it should normally work:
http://www.tchnws.de/webdesign/responsive-dropdown-menu-mit-css-und-jquery-erstellen-in-verbindung-mit-dem-superfish-menu

I also tried deactivating all of my plugins, but it still wasnt working.

Any Help is appreciated, thank you guys!

http://wordpress.org/extend/plugins/syntaxhighlighter/