Some .CHM files may not render properly on Windows Vista and Windows 7

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Article ID: 2021383 - View products that this article applies to.
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When attempting to open a Compiled HTML Help (.CHM) file on Windows Vista or Windows 7, the file may open but display one of the following messages instead of the expected content:

  • Navigation to the webpage was canceled.
  • Action canceled.


This will occur if the .CHM file has been flagged as downloaded from an untrusted source, such as the Internet.


To resolve this issue, carry out the following steps:

  1. Right-click the .CHM file and choose Properties
  2. On the General tab, click the button labeled "Unblock"
  3. Click OK

More Information

This behavior is a function of the Attachment Manager, which applies a Zone Identifier to files downloaded from any source that is considered untrusted or at risk, such as the Internet Zone.
Note This is a "FAST PUBLISH" article created directly from within the Microsoft support organization. The information contained herein is provided as-is in response to emerging issues. As a result of the speed in making it available, the materials may include typographical errors and may be revised at any time without notice. See Terms of Use for other considerations.


Article ID: 2021383 - Last Review: March 23, 2010 - Revision: 2.0
  • Windows 7 Enterprise
  • Windows 7 Home Premium
  • Windows 7 Professional
  • Windows 7 Ultimate
  • Windows Vista Business
  • Windows Vista Business 64-bit Edition
  • Windows Vista Enterprise
  • Windows Vista Enterprise 64-bit Edition
  • Windows Vista Home Basic
  • Windows Vista Home Basic 64-bit Edition
  • Windows Vista Home Premium
  • Windows Vista Home Premium 64-bit Edition
  • Windows Vista Ultimate
  • Windows Vista Ultimate 64-bit Edition

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