There seems to be a bug in the Service Pack 2 for ISA server 2K4. I get errors when launching some websites. The issue disappears when SP2 is not installed. For example, when I go to www.sun.com, the images don't load at all. When I go to www.delta.com, I get the following error page from the ISA server: Error Code: 502 Proxy Error. The HTTP request includes a non-supported header. Contact your ISA Server administrator. (12156) I did a lot of searching through the web and there were some workarounds provided, which did not work at all. If there's some setting that can be tweaked in order to have ISA allow these sites, then I would appreciate any help. Thanks.