Opening an HTML Help (*.chm files) which is stored on a released network folder has the effect that no topic are displayed (under Windows).
This error occurs because Windows automatically blocks the contents of .chm files on a network folder which are opened via a UNC path (Universal Naming Convention) for reasons of security. This happens as of Windows Security Update 896358 or Windows Server 2003 Service Pack 1 which have been implemented to remove security gaps in the HTML Help. Problems concerning the HTML Help may also occur with the security update 840315 because only files ending on *.chm are used as HTML Help files.
This problem requires particular specifications to be made in the Windows Registry in order to have HTML Help contents correctly displayed on a network folder. You may either release particular URLs or a complete security zone.
1. Releasing individual URLs:
Individual URLs may be released in the registry path
using the value "UrlAllowList". Example:
The network folder: \\docu\htmlhelp\uc4\ should be released. Doing so requires the following line to be copied in a file ending on *.reg (note: it is always recommended to backup your registry before making any changes):
REGEDIT4 [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\HTMLHelp]Now execute this file.It is also possible to change the relevant value manually via the Registry Editor (Process: regedit). Two registry entries must be added in order to release a UNC path to a network folder:
2. Activating a security zone:
The term zone refers to a particular network area. Windows knows 5 different security zones. The registry value "MaxAllowedZone" may be used to define the number of released zones. The following impacts result from the values specified in "MaxAllowedZone". Default setting: 0.
The Automic HTML Help is always correctly displayed when the setting MaxAllowedZone=3 has been specified. Example:
The registry entry "MaxAllowedZone" uses value 3.
To have this value entered in the Registry, execute a .reg file with the following line (note: it is always recommended to backup your registry before making any changes):
REGEDIT4 [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\HTMLHelp]This setting may also be specified manually via the Registry Editor.