CHM files not rendering properly

Some .CHM files may not render properly on Windows Vista and Windows 7. The file may open but display the following messages instead of the expected content:

This issue can happen for three different reasons:

1. The file is blocked

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

(Note: this issue is described in the Microsoft Support center as Article ID 2021383)

2. The file is located on a shared network folder

Microsoft released a security patch that makes it impossible to view CHM files that are stored on a network drive (as opposed to CHM files stored on your own computer).
To work around this issue, copy the CHM file onto your local computer before opening it.

3. The path to the file contains a number sign (#)

If the CHM file name or the path to the file contains a number sign (#), you will not be able to open the file. To work around this issue, remove the # symbol from the file name or from the path to the file.
(Note: this issue is described in the Microsoft Support center as Article ID 319247)