Help file located on network drive does not display

Microsoft Security Update 896358 disabled the use of .chm files when they are located on a network drive. See MS knowledge base article http://support.microsoft.com/?kbid=896358 for the details.

In summary, there are two solutions. Both solutions require changes to the registry, so proceed with caution; better yet, ask your system administrator!

To enable ALL access to .chm files on any network location:

Locate the key:

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\HTMLHelp\1.x\HHRestrictions]

and set the value of MaxAllowedZone to 1

To enable access to .chm files in a specific folder only:

Locate the key:

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\HTMLHelp\1.x\ItssRestrictions]

and create a string value called UrlAllowList and give it a value of

\\hostname\sharename\;file://\\hostname\sharename
 
where hostname is the name of your server and sharename is the folder path where the .CHM files are located. This method can be deployed on all PCs on your intranet by using a Group Policy object.