Microsoft Internet Explorer may lose the first 2048 bytes of data that are sent back by a Web server when the Web server uses Hypertext Transfer Protocol (HTTP) compression. This issue occurs when a program registers a name space handler for any of the following protocols:

•	HTTP
•	HTTPS
•	File Transfer Protocol (FTP)
•	Gopher
•	File

For example, Real Download registers name space handlers for HTTP and FTP. This loss of data causes script errors, poor display of Hypertext Markup Language (HTML) elements, and so on.

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This issue occurs because there is a problem with the Urlmon.dll file when the file binds specifically to notify programs that have registered name space handlers.

The problem occurs if any of the following keys are in the registry:

•	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

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A supported fix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Apply it only to computers that are experiencing this specific problem. This fix may receive additional testing. Therefore, if you are not severely affected by this problem, Microsoft recommends that you wait for the next Internet Explorer 5.5 service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site:NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The typical support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

The English-language version of this fix should have the following file attributes or later:

   Date         Time      Version        Size     File name
   ---------------------------------------------------------
   08-JAN-2002  13:56:15  5.50.4913.700  451,856  Urlmon.dll
				

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WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.


To work around this problem, use one of the following methods:

•	Disable HTTP compression (you can do this by using either HTTP 1.0 on the client or by changing the Web server's configuration).
•	Delete any of the registry keys that are in the following location: HKEY_CLASSES_ROOT\Protocols\Name-Space Handler Note that this prevents the program that registered that name space handlers from working as expected.
•	Uninstall the program that registers name space handlers for one of the protocol listed above.

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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.

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