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.

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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] "CLSID"="{EBCDDA5E-2A68-11D3-8A43-0060083CFB9C}" "CLSID.new"="{EBCDDA5E-2A68-11D3-8A43-0060083CFB9C}"
•	[HKEY_CLASSES_ROOT\PROTOCOLS\Name-Space Handler\http\RealDownload] "CLSID"="{EBCDDA5E-2A68-11D3-8A43-0060083CFB9C}" "CLSID.new"="{EBCDDA5E-2A68-11D3-8A43-0060083CFB9C}"

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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:

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

File information

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
				

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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 (http://support.microsoft.com/kb/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.

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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.

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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.

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