Win7 and *.chm file not showing content

Old help files (*.chm) is sometimes not showing on Win7 computers. They are showing with "Navigation to the webpage was canceled" as picture below:

To be able to view the content of the *.chm file you need to do the following:

1. Have the file locally (i.e. not on a network drive of WebDAV area)
2. Unblock the file (file properties > Unblock)
   

Unblock files with cmd-line
It's possible to unblock files with the cmd-line utility Streams from Sysinternals; Streams.exe -d Filename.chm