Error 400-403 from local network

[JF002]

Hi !

I'm currently trying to install Nginx/Php-fpm. 

In fact, every thing seem to be ok: I can access to html and php pages
using the local address (192.168.0.4/index.html, for example,
192.168.0.4 is the IP address of my nginx server).

Then, I created a No-Ip dynamic DNS. If I ping the DDNS address from
another computer on the local network, it pings my nginx server
(192.168.0.4).
On ALL on my computers (a laptop on WinXP, a Windows Mobile Phone, an
iPod Touch, a virtual machine on Ubuntu), I can access to my nginx
server using the DDNS addressn without doing any configuration on these
devices

On all computer... except one! This is my main computer, running on
Win7. Pinging the DDNS address returns the correct local IP address of
the Nginx server but when I want to display a page, I only have a blank
page. Chrome (using the developer tool) says that an Error 403
(forbidden) occurs. Using the local IP address directly works fine. I
have the same behaviour with Chrome, Firefox and IE, only on this
computer.

I tried to debug this problem, with no luck. Using Wireshark, I saw that
it seems that no GET request is sent. I tried to clear cache, flush DNS,
disabling anti-virus/firewall,... Nothing!

In the file access.log, I see that a line is added each time I request a
page from this computer (192.168.0.2 is the IP address of the computer
on which the problem occurs):
192.168.0.2 - - [12/Jul/2012:00:06:25 +0200] "-" 400 0 "-" "-"


Yeah, my problem is probably not caused by Nginx, but seriously, I don't
know where to look!

Can you help me, please?

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,228518,228518#msg-228518