Firewall Issue

[eluser]Unknown[/eluser]
hi all,
I have a site(www.koovs.com) running on CI. While my site works flawlessly on non secured networks,but it gives a blank screen on systems secured by firewall.
Now what's baffling is that even in secured systems i am able to get the correct response hitting http://www.koovs.com/test.php but hitting http://www.koovs.com gives me same blank page.
Also while discussing with a firewall guy, he said that my site works if we disable http scanning option in the firewall. He also added that this happens if there is a virus or looping in the code base,but I havent found both.
I am loosing my half of traffic because of this. Please help!!!!