WordPress on a Nginx server with 2mil monthly hits???

I’m hoping I can get an answer to this tonight but I’m sure it’s highly unlikely… Anyhow, I have a server which the client has already started using Nginx instead of Apache for it’s HTTP server… the thing is, now that he has switched, he’s getting 502 Bad Gateway errors on his WordPress site.

I’ve viewed the log file and all I keep seeing is:

2012/05/25 21:58:26 [error] 3782#0: *2377747 connect() to unix:/home/xxxxxxx/.php.sock failed (11: Resource temporarily unavailable) while connecting to upstream, client: 68.45.24.61, server: xxxxxx.com, request: “GET / HTTP/1.1”, upstream: “fastcgi://unix:/home/xxxxxx/.php.sock:”, host: “www.inflexwetrust.com”

I’ve done some googling, but I have to say, I’m completely ignorant to this type of situation, much less in using Nginx… Apache is my thing… I mean I recommended that he switch back to Apache, but he’s adamant on using Nginx due to it’s decreased memory usage at his amazingly high traffic rate….

I’m at my wits end… and googled to death… hopefully I can turn to you guys to gimme a hand ??

Oh and FYI, this server is running around 2,000-5,000 concurrent connections at any given time….