Enabling Access Control in Web Proxy May Return a Blank Page

If you enable access control and defined a valid Microsoft Windows NT user or group account in Proxy Server 2.0 installed over Internet Information Server version 4.0 (IIS), the Web Proxy clients may fail to connect and display one of the following error messages:

NOTE: The error message depends on the browser you use.

Microsoft Internet Explorer version 4.0 and 4.01: Microsoft Internet Explorer version 3.02: Netscape Navigator version 3.02:

This issue is caused by a problem with the authentication settings in IIS 4.0 and the Web Proxy ISAPI filter.

To resolve this problem, obtain the latest service pack for Windows NT 4.0. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

Microsoft has confirmed this to be a problem in Microsoft Internet Information Server version 4.0.

Use one of the following methods:

Method 1

Disable Access Control in Web Proxy Service by opening the Web Proxy Properties within the MMC and go to the Permissions tab. Clear the Enable Access Control check box.

Method 2

Disable Anonymous access for the default web site in IIS 4.0.

NOTE: This will enable Proxy clients to connect to the Internet; however, it does not allow anonymous users to connect to the default web site if the server is also used for Internet publishing.