WordPress and nginx, download some pages instead of serving them

Today i setup wordpress with nginx. The problem, i cant figure out, is that some pages will be served as expected and some other will be served as download. If i download them, the content is the sama as index.php in wordpress root folder. I tried to find some differences between the “normal” pages and the other defective pages, but cant find anyone.

The funny thing is, if i give that faulty pages another permalink (e.g. ../funktionen -> ../features, the pages will be served correctly. If switch back to old old permalink, the page will be served as download.

Here is my nginx conf:

#redirect
#  http://www.termin2go.com and
#  http://termin2go.com
# to
# https://www.termin2go.com
server {
        listen 80;
        server_name termin2go.com www.termin2go.com;
        rewrite ^(.*) https://www.termin2go.com$1 permanent;
}


# redirect
#   https://termin2go.com
# to
#   https://www.termin2go.com
server {
        listen 443 ssl;
        server_name termin2go.com;
        rewrite ^(.*) https://www.termin2go.com$1 permanent;
}

server {
        listen 443 ssl;
        server_name www.termin2go.com;
        ssl_certificate /etc/ssl/private/www.termin2go.com.crt;
        ssl_certificate_key /etc/ssl/private/www.termin2go.com.key;

        access_log  /var/log/nginx/termin2go.com.log;
        error_log /var/log/nginx/termin2go.com_error.log;
        set $root_path '/var/www/wordpress';
        root $root_path;
        charset utf-8;
        client_max_body_size 7M;

        # DEFAULT INDEX
        index index.php;

         # configure prerender for snapshot generation
        location / {
                try_files $uri $uri/ /index.php?$args @prerender;
        }
        location ~ /(.|wp-config.php|liesmich.html|readme.html) {
                return 444;
        }

        # REWRITES
        location ~ ^/(d+)/$ {
                return 301 /?p=$1;
        }

        # fix whitespace in url bug
        if ($request_uri ~ " ") { return 444; }

        # redirect google bot to prerender for ajax content (AngularJS)
        location @prerender {
                proxy_set_header Host $host;
                proxy_set_header X-Real-IP $remote_addr;
                proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
                #proxy_intercept_errors on;

                set $prerender 0;
                if ($http_user_agent ~* "googlebot|yahoo|bingbot|baiduspider|yandex|yeti|yodaobot|gigabot|ia_archiver|facebookexternalhit|twitterbot|developers.google.com") {
                        set $prerender 1;
                }

                if ($args ~ "_escaped_fragment_|prerender=1") {
                        set $prerender 1;
                }

                if ($http_user_agent ~ "Prerender") {
                        set $prerender 0;
                }

                if ($prerender = 1) {
                        rewrite .* /$scheme://$host$request_uri break;
                        proxy_pass http://127.0.0.1:4000;
                }

                if ($prerender = 0) {
                        rewrite .* /index.php break;
                }
        }

                # cache static files one month
        location ~* .(css|cur|js|jpe?g|gif|htc|ico|png|html|xml|otf|ttf|eot|woff|svg)$ {
                expires 31d;
                add_header Pragma "public";
                add_header Cache-Control "public, must-revalidate, proxy-revalidate";
        }

 # cache static files 30 days
        location ~* .(css|cur|js|jpe?g|gif|htc|ico|png|html|xml|otf|ttf|eot|woff|svg)$ {
                expires 31d;
                add_header Pragma "public";
                add_header Cache-Control "public, must-revalidate, proxy-revalidate";
        }

        # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
        #
        location ~ .php$ {
                try_files $uri =404;

                fastcgi_split_path_info ^(.+.php)(/.+)$;
                #NOTE: You should have "cgi.fix_pathinfo = 0;" in php.ini

                include fastcgi_params;
                fastcgi_index index.php;
                fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
                #fastcgi_intercept_errors on;
                fastcgi_pass unix:/var/run/php5-fpm.sock;
        }

        # prevent nginx from serving dotfiles (.htaccess, .svn, .git, etc.)
        location ~ /. {
                deny all;
                access_log off;
                log_not_found off;
        }
}