Guarddog blocking http to lan in gateway box?

Hello!

I'm using Guarddog (version 2.6.0-2.1) in a Debian (Lenny) box.
I'm having problems trying to use that box like internet gateway. I 
tried both using guidedog or using iptables MASQUERADE.

The problem occurs only with http any other protocols works ok from the 
computers within the lan. Really I couldn't find anything in logs.
Does guarddog applies some specific filtering that could block http?

I tried disabling guarddog from the gui, but problem persists.

This link is a question I did on the same issue:

http://www.linuxquestions.org/questions/linux-networking-3/http-not-working-with-guidedog-like-router-725080/

Thanks in advance,
Matías


------------------------------------------------------------------------------
Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT 
is a gathering of tech-side developers & brand creativity professionals. Meet
the minds behind Google Creative Lab, Visual Complexity, Processing, & 
iPhoneDevCamp as they present alongside digital heavyweights like Barbarian 
Group, R/GA, & Big Spaceship. http://p.sf.net/sfu/creativitycat-com