Nginx apache wordpress problem

I'm using nginx as proxy reserve for apache and install wordpress. The problem is firefox keep getting error "The page isn't redirecting properly" but there's no problem with opera.
Here is the nginx virual host conf.

Please help

 

have you given read/write permissions to nginx on /home/webgua/public_htm?

 

Thx for replayed. I found there should add :
proxy_redirect off;
proxy_set_header Host $host;
and now it works good.