I use Firefox version 19.0.2
I found a way to fix this error for me. I change the code in this:
PHP Code:
$moduleContainer->add(new Comment("<a href=http://treeofarvalus.de/languages/de>Deutsch</a> <a href=http://treeofarvalus.de/languages/eng>English</a>"));
Don't know why exactly it need the 'http://'-Part in front of the link, but now it works.