IE pauses before opening websites

Whenever I connect to a web site, or follow a link in Internet Explorer it hangs for approximately 20 seconds before continuing. I have tried IE 5.5 and upgraded to IE 6 SP1 and the problem still exists.

I am connecting to the internet via my work LAN. The network runs Microsoft ISA server as the proxy software. My fellow colleagues don’t suffer from the same problem. We do run virus scanning software which I thought may be the issue. However, the helpdesk has deactivated this software for me temporarily and the problem still exists after a reboot.

I’m using a brand name PC (Compaq) running Windows NT4 workstation.

Any help would be appreciated.