Error Accessing and Displaying CHM Files: Reasons and Solutions
http://www.drexplain.com/press/chm-files-the-page-cannot-be-displayed-error/

Crane, Dennis
Dr. Explain
2006

Abstract:

So, you've got in trouble. Some or even all of your CHM files seem to have gotten corrupted. They show a "The page cannot be displayed" error in the left-hand pane of the CHM viewer. There are several possible reasons why your CHM e-books and documentation files are unreadable.