Geosolve Consultant: Dr Daniel Borin
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Problems with viewing WALLAP, SLOPE and GWALL Help files (.CHM files)

"Action cancelled" 
cannot read Help Topics 

CHM files downloaded from a website cannot be viewed
Due to excessive caution on the part of some Windows systems you may get an "Action cancelled" message on opening a CHM file which you have downloaded from a website.

The work around is as follows. In Windows Explorer, right click on the CHM file name and select Properties.
Click "Unblock" and "Apply".

"This program cannot 
display the webpage" 

Help files not displayed correctly across a network 
When viewing CHM files (WALLAP, SLOPE or GWALL Help), you may see the message:
                        "This program cannot display the webpage"

If the Contents displays OK, but the help text does not, then you are probably viewing your CHM file over a network. Microsoft in its wisdom decided that CHM files were a security risk because you can embed ActiveX's, external links to exe's etc. So, they released a Windows Critical Update, KB896358, which effectively means that CHM files can not be viewed on a network shared folder.

This problem applies to all CHM files on a network. If you view the CHM file from your local disk, i.e. the C drive, it will display as expected.

Geosolve has attempted to solve this problem by getting WALLAP to make a copy of the CHM file on your local Hard Disk. If the problem persists then you should implement the following :

The solution is to add a MaxAllowedZone registry value and to set it to at least 1, as this permits access to HTML Help files stored both locally (Local Machine zone) and remotely (Local intranet zone). In case that is something you donít feel entirely comfortable with there is a handy utility which you can download from

If you want to apply this fix, open the zip file and double-click the reg file and the setting will be added to your Registry. This needs to be done on each workstation that access CHM files on the server.
Revised December 2019