Internet Explorer May Lose the First 2,048 Bytes of Data That Are Sent Back from a Web Server That Uses HTTP Compression (312496)

IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry

SYMPTOMS

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:

File
FTP
Gopher
HTTP
HTTPS

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.

CAUSE

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}"

RESOLUTION

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

WORKAROUND

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

Disable HTTP compression by changing the Web server's configuration.
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.

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.

STATUS

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.

MORE INFORMATION

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.