502 Bad Gateway error on 1 of my sites

[befree22]

I added a brand new new domain to my Centos 6 vps with nginx recently. I uploaded Wordpress and configured the database and WP config file. I'm unable to install Wordpress http://www.mydomain.com/wp-admin/install.php until this problem is fixed.

1. All other sites on my vps load fine and all sites were migrated from another vps provider.
2. This new site pings correctly when I test it on a ping site.
3. The vps provider said that the error is with an .htaccess file or a plugin since other sites load fine. I did a plugins_bak to disable all plugins but the error persists. All sites have same plugins installed.
4. I started having this problem after I renamed the Kloxo-MR index.html to index.html_bak (cause other sites had index.html_bak). I switched it back to index.html. Also, I ftp'd a theme into Wordpress which I renamed with _bak but problem still persists.
5. I tried adding a blank .htaccess file but Kloxo-MR won't save it. None of my sites have .htaccess file on Kloxo-MR which is odd since they all had .htaccess on DirectAdmin. No complaints here but I guess it's a security measure with Kloxo-MR.

Any ideas on how to fix this?

[prandah]

how many domain on your server?
try use old trick
switch to lighttpd
then switch back to your own

[befree22]

how many domain on your server?
try use old trick
switch to lighttpd
then switch back to your own

I have 6 live sites on the server.
How do I switch from nginx to lighttpd? Is this a Putty command? Or is this in Kloxo-MR admin? Which icon?

FYI: I did a backup of all files.

[zenkul]

at kloxo-mr panel

imho
server : linux  + switch program ====> nginx-proxy
web-mail-database + web server config + php type =====> php-fpm event