Have you ever seen this kind of message when you try to see a help file (.chm). The same files sometimes are displayed in WindowsXP without a problem. Vista opens the file, but fails with a “The address is not Valid” error. Even after confirmation to allow the content of the file.

The Solution Is pretty Simple…

A solution i found somewhere

• Double-click the .chm file.
• In the Open File-Security Warning dialog box, click to clear the Always ask before opening this file check box.
• Click Open.

The Solution that worked for me is

• Right-click the CHM file, and then click Properties.
• Click Unblock.
• Double-click the .chm file to open the file.