Problem:
When clicking on 'Help', the help file opens, and the contents list can be navigated, but the display panel shows an error message as shown:

Cause:
Since the introduction of Microsoft Security Update MS05-026, chm files (i.e. help files) located on a server will not work properly, most commonly clicking a topic in the table of contents displays a Page Cannot Be Displayed message.

Solution:
The following workaround has been developed but you should carry out your own research into this Security Update before attempting the modification.

If the task below does not appear easy to perform, or if you are unfamiliar with registry modifications, then you should seek advice from your IT technician:

Locate the key:

HKEY_LOCAL_MACHINESOFTWAREMicrosoftHTMLHelp1.xItssRestrictions

and create (or edit) a string value called UrlAllowList. Give it a value of

\\hostname\sharename\content\help;file://\\hostname\sharename\content\help

where hostname is the name of your server and sharename is the folder share name - the folders indicated in the path reflect the path to the folder containing the help file .CHM.

After verifying that the Help function works on a single workstation, this key change could be deployed on all PCs on the domain using a Group Policy object.

See also http://support.microsoft.com/default.aspx?scid=kb;en-us;896054 if these instructions appear incomplete or difficult to follow.