Everything was OK with Internet Explorer. Since I installed Firefox 3.6, some Web pages won't load. Sometimes when clicking several times on "reload current page" page displays for 1-2 seconds, sometimes it would stay but when I click any item on that page, problem re-starts again. Example: www.ebay.com or www.ebay.fr, or speed test page http://mire.ipadsl.net that hangs for ever.
Firefox has all four items checked in Program Control of ZA and has a green dot when active. Program options are default ones. No valid solution found on Firefox Forum except one proposal to change the firewall !