Internet Explorer May Lose the First 2,048 Bytes of Data That Are Sent Back from a Web Server That Uses HTTP Compression

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Article ID: 312496 - View products that this article applies to.
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Internet Explorer may lose the first 2,048 bytes of data that are sent back from a Web server that uses Hypertext Transfer Protocol (HTTP) compression. This problem occurs if a program has registered a namespace handler for any of the following protocols:
One example of such a program is the Real Download software (which is available in a full installation of Real Player Basic). This program registers namespace handlers for HTTP and FTP. The data loss may manifest itself in script errors or incorrectly displayed HTML elements.


The behavior is caused by a problem in Urlmon.dll. The problem occurs when Urlmon.dll binds specifically to notify programs that have registered namespace handlers. The problem occurs if any of the following registry keys is present:
  • HKEY_CLASSES_ROOT\PROTOCOLS\Name-Space Handler\http
  • HKEY_CLASSES_ROOT\PROTOCOLS\Name-Space Handler\ftp
  • HKEY_CLASSES_ROOT\PROTOCOLS\Name-Space Handler\gopher
  • HKEY_CLASSES_ROOT\PROTOCOLS\Name-Space Handler\https
  • HKEY_CLASSES_ROOT\PROTOCOLS\Name-Space Handler\file
Real Download 8 registers the following keys :
  • [HKEY_CLASSES_ROOT\PROTOCOLS\Name-Space Handler\ftp\RealDownload]
  • [HKEY_CLASSES_ROOT\PROTOCOLS\Name-Space Handler\http\RealDownload]


To resolve this problem, obtain the latest service pack for Internet Explorer 6. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
328548 How to Obtain the Latest Internet Explorer 6 Service Pack
The English version of this fix should have the following file attributes or later:
   Date         Time   Version       Size     File name
   08-Jan-2002  11:56  6.0.2713.800  480,256  Urlmon.dll


To work around this problem, use any of the following methods:
  • Disable HTTP compression by changing the Web server's configuration.
  • Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
    322756 How to back up and restore the registry in Windows

    Delete any of the registry keys that are listed earlier in this article in the HKEY_CLASSES_ROOT\PROTOCOLS\Name-Space Handler key. Note that using this method this prevents the program that registered the namespace handler from working as you expect.
  • Remove the program that registered the namespace handler for one of the protocols that is listed earlier in this article.


Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article. This problem was first corrected in Internet Explorer 6 Service Pack 1.


The third-party products that are discussed in this article are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, regarding the performance or reliability of these products.


Article ID: 312496 - Last Review: January 31, 2007 - Revision: 3.11
  • Microsoft Internet Explorer 6.0, when used with:
    • Microsoft Windows XP Home Edition
    • Microsoft Windows XP Professional
    • Microsoft Windows XP Media Center Edition
    • Microsoft Windows XP Tablet PC Edition
    • Microsoft Windows 2000 Advanced Server
    • Microsoft Windows 2000 Datacenter Server
    • Microsoft Windows 2000 Professional Edition
    • Microsoft Windows 2000 Server
    • Microsoft Windows NT Server 4.0 Standard Edition
    • Microsoft Windows NT Server 4.0, Terminal Server Edition
    • Microsoft Windows NT Workstation 4.0 Developer Edition
    • Microsoft Windows 98 Second Edition
    • Microsoft Windows 98 Standard Edition
kbhotfixserver kbqfe kbbug kbfix kbie600presp1fix kbie600sp1fix KB312496

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