YES YOU'R right!
i didn't know that the /cgi-bin dir was an alias and so "linked" direct into the web. when i now point to www.muv.local/cgi-bin/hello_world.pl
i am a little bit better. til now i got a 404 file not found. from now on i get a 500 internal server error. i think this is a little bit better. the next thing to do is to check the log-files. i'l do this tomorrow!