Emergancy Please Help me immediately

Here is a problem that I am using outlook express on my PC and at the front end there windows 2000 server using MS-Proxy 2.0 running.When I add hotmail folders account in my outlook in windows 2000 it is added but when trying to sycronize with hotmail’s http web server it shows a message “Proxy authenticaton required”.Please help me that how to resolve this problem.