为什么80端口打不开index.php改成其他端口就可以

nginx->vhost
listen 改成8080就能打开index 改成80就打不开，请高人指点一下怎样修改能用80端口打开网站？
server {
        listen       80;
        server_name  localhost;
        index index.html index.htm index.php;
        root /alidata/www/prestashop;
        location ~ .*\.(php|php5)?$
        {
                #fastcgi_pass  unix:/tmp/php-cgi.sock;
                fastcgi_pass  127.0.0.1:9000;
                fastcgi_index index.php;
                include fastcgi.conf;
        }
        location ~ .*\.(gif|jpg|jpeg|png|bmp|swf)$
        {
                expires 30d;
        }
        location ~ .*\.(js|css)?$
        {
                expires 1h;
        }
        
        #include /alidata/server/nginx/conf/rewrite/phpwind.conf;
        access_log  /alidata/log/nginx/access/prestashop.log;
}