You cannot connect to the Internet after you install Microsoft updates

You cannot connect to the Internet after you install any of the following Microsoft updates:

• Internet Explorer 6 Service Pack 1 (SP1)
• Microsoft Windows XP SP1
• The hotfix that is described in the following Microsoft Knowledge Base article:
  312176� Heavy NTLM Authentication Traffic Occurs Between Internet Explorer and the Proxy Server
• The hotfix that is described in the following Microsoft Knowledge Base article:
  325662� NTLM Authentication Over an SSL Connection Does Not Work in Internet Explorer 6

This problem may occur if you are using a third-party proxy product that uses only basic authentication.

The following file is available for download from the Microsoft Download Center:
For more information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base: Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help prevent any unauthorized changes to the file.
The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.

Microsoft has confirmed that this is a problem in the updates that are listed in the "Symptoms" section of this article.

If you use Microsoft Windows NT Challenge/Response (or NTLM) authentication with Microsoft Internet Security and Acceleration (ISA) Server 2000 or with Microsoft Proxy Server 2.0, you may experience the following behavior after you install the hotfix that is described in this article:

• You receive incomplete HTML pages.
• You are randomly prompted for authentication credentials.
• NTLM authentication traffic may appear in the ISA Server top-ten report.

For more information about this problem, click the following article number to view the article in the Microsoft Knowledge Base: