Consider the following scenario:

•	You develop an application filter for Microsoft Internet Security and Acceleration (ISA) Server 2006.
•	This application filter establishes an HTTP connection.
•	An S_OK value indicates that the connection has been successfully established.

In this scenario, the connection closes before it can be used. If you have enabled ISA logging, a "0x80004001 (E_NOTIMPL)" status code is logged.

This problem occurs only if the Web Proxy Filter is enabled for the HTTP protocol.

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This problem occurs because the Web Proxy Filter incorrectly uses sockets and connections that are created by other application filters. Therefore, the Web Proxy Filter cannot be chained to other application filters.

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To resolve this problem, apply the hotfix rollup package that is described in Microsoft Knowledge Base article 942639. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

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Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

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