It seems to have solved the initial problem!
Now I get this error:
The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there was an error in a CGI script.
The error log states:
[error] [client 10.0.0.10] Syntax error in type map, no ':' in /srv/www/htdocs/index.php for header <?php\r\n
It ends right there ...
I do not even know what a cgi script is, and I never needed it when i used Apache and PHP on windows (I used the WAMP package).
There is a folder named cgi-bin in /srv/www with one file in it, named php5.