Problem with Fortiguard URL Filtering

[#1]

Hi community, I have some problem with URL Filtering using Fortiguard Web Filtering I have try some different configuration but the resault is the same. When enabling FortiGuard Web Filtering and I try to access to some site (example www.cisco.com or some web mail site) the browser (IE 8) give me the error HTTP 408/409 only from some computer. With all other site we didn' t had any problem. I try to set FortiGuard Web Filtering to permit all site, but the resoult is the same. The computer and the Fortinet80C are all on the same CLASS C network. The sw version of my Fortinet is v4.0,build0291,100824 (MR2 Patch 2) Does someone already had this problem?

[#2]

The second image of my configuration

[FortiRack_Eric]

Enable Provide details for Blocked HTTP 4xx and 5xx errors Cheers, Eric

[#4]

I enable it, but the problem still remain.

[FortiRack_Eric]

What is the error message now?

[#6]

Now I try to clear the IE cache/cookie/temp file and now the problem HTTP 408/409 error seems to be solved. I' m able to view the cisco site. Now on some site (like webmail or ecommerce site) we have the classic IE error the page can not be displayed when we try to perfmor the login on the web site