Cannot read CHM file in Windows 7

If you can't read pages in a CHM (Compiled HTML) file on a Windows 7 computer, you might have to "unblock" the file. Seems to be a security feature to prevent scripts running.

1. Show the CHM file properties.
2. In the General tab, press the Unblock button. Note: After you do this, the button no longer appears for this file.

Thankfully, you only need to do this one time for the CHM file.

See longer write-up in StackOverflow.