Do you see 'Page not displayed' or 'Navigation to the web page was cancelled' when you try to open a .chm file?
I have found that you do not need any software to view the file. These files coming from third party server are by default blocked. Hence you just need to unblock them in many instances to view them.
1. Right click the file and select 'Properties'
2. Click Unblock
Other known issues for error with .chm file
1. Check for any hash/sharp symbol in the filename. Rename your file without using any symbols. This is a known bug with all Window versions.
2. CHM viewer component not registered on your PC - Run regsvr32 hhctrl.ocx in the command line(Start>>Run) to register the library in the system.
When the .chm file is on other network drive:
1. Go to Run and type regedit
2. Locate HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\HTMLHelp\1.x\ItssRestrictions. Create the registry key, if it does not exist
3. Right-click ItssRestrictions, select New, and then click DWORD.
4. Type MaxAllowedZone, and then press ENTER.
5. Right-click the MaxAllowedZone value, and then click Modify.
6. In the Value data box, type a number from 0 and 4, and then click OK.
0 = My Computer
1 = Local Intranet Zone
2 = Trusted sites Zone
3 = Internet Zone
4 = Restricted Sites Zone
For most CHM files, the value of 1 should be enough to allow use without opening up access from/to remote CHM files in email/internet locations.