When installing the copy and even explicitly set English as the default language the default SEO URL language is still set to German. I guess is this will not be touch it should be fine but if you change it to English all the SEO URL prefixing, i.e. /de /en is screwed up and will not be restored even when the change is immediately reversed.
Master Settings -> Core Settings -> Primary language for SEO urls — by default even if English as the default was chosen it set to German — set this to English and it will screw up all the SEO URLs to some like http://www.domain.com/index.php?cl=info&tpl=agb.tpl.
Switching that back to German make the http://www.domain.com/index.php?cl=info&tpl=agb.tpl work strangely enough though, but the SEO URL’s are gone.
Just notice that all the product and category URL’s don’t work anymore when switching back as the SEO URL’s are no longer be prefixed with /en/ or /de/.
-.> Rico