After registration / 502 Bad Gateway

[chckrs]

Hello,

 

So today I found out that when I try to register for a new account in my webshop, it redirects to a page where it only shows:

 

502 Bad Gateway

nginx/1.0.0

 

 

When you get back or refresh, there is an error saying the mailadress is already used and there is actually an e-mail send to the user for registration. Now since that works, the only problem is the 502 page showing up, how can I fix this? the page trying to load is: http://totalinbalance.com/webwinkel/authentication.php

 

website: http://www.totalinbalance.com/webwinkel/

 

 

(it's only in Firefox/IE, not in google chrome?!!)