sbw_masc

Thanks a lot!

That helped me a lot. I found a custom gzip compression in the functions.php

// enable php gzip-compression
function wp_gzip ()
{
	ob_start('ob_gzhandler');
}
add_action('init','wp_gzip');

After removing this part it worked perfectly.

Is there any way to find out why the page crashes? Something like enabling a special debugging mode?