What can cause images to not show in HTML Help (chm files) if UAC is Enabled?

Question

On a computer running Windows 7 Embedded Standard (SP1), 64 bit, I am not able to view images in any chm files unless UAC is turned completely off.

All of the images are replaced with a small black and white box with an "X" in it.

Things I've tried:

• If I transfer the chm files to a different Windows 7 Embedded computer running the exact same version of IE (11.0.9600.18230), the chm files work perfectly, even if UAC is set to "Always Notify".

• None of these chm files come from the internet.

• No paths to the chm files has a # in it. Even if I copy it to the desktop or C:\ (my user folder is on the D:) I still don't see images.

• Internet Explorer is set to display images

• There's no "Unblock" button in the properties shown for any chm file

• This help file is not on a network drive, and I'm not running Windows XP, but I tried this ItssRestrictions registry fix anyway. I tried setting it to 1, then I set it to the least restrictive setting (4), no effect.

• I have tried running regsvr32 to register hhctrl.ocx, itss.dll, and itircl.dll.

• If I view the chm file using SumatraPDF, it works perfectly, even as a non-administrator when UAC is enabled.

• If I load the help file by running hh.exe from command line as administrator, images work properly. Images don't load if hh is run by a normal user.

• If I open the chm file in 7-zip and extract all of the html documents and open them in IE11, the images work even if UAC is enabled.

• Internet explorer settings for "Trusted sites" is set to "Low", and I have added "localhost", "127.0.0.1", and the computer's name as trusted sites.

• MJ's help report for the working computer

• MJ's help report for the non-working computer

Is there anything else I could try to narrow down the possible causes of this problem?

Are there any other security settings that can affect chm files?

Other related questions

• Windows CHM file only displays images for Administrator (Windows 2000) (no answer)

Answer 1

I've had this problem with an XP computer (not Seven) for years. I'm far from being a superuser so I managed to keep it this way for years! But recently I had a "stupid" idea. Went and see in IE advanced config... (This is not my default browser). The "show image" option was simply unchecked. I checked the box and guess what? It worked! I can see the image in CHM_help files again! Maybe it can help...

Answer 2

In my case this was solved this by clearing the read-only attribute of the INetCache folder in Window's local Appdata folder. Source

Answer 3

I had the same problem but never touched UAC.

There are apparently different levels of authentication for the HTMLHelp MaxAllowedZone registry. Most articles I read tell you to set the MaxAllowedZone to '1' which means that local machine zone and intranet zone are allowed but '4' allows access for 'all' zones.

For more info, read this article: https://support.microsoft.com/en-us/kb/892675

This is how my registry looks (I wasn't sure it would work with the wild cards but it seems to work for me):

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\HTMLHelp]

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

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\HTMLHelp\1.x\ItssRestrictions]
"MaxAllowedZone"=dword:00000004

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\HTMLHelp\1.x\ItssRestrictions]
"UrlAllowList"="\\\\<network_path_root>;\\\\<network_path_root>\*;\\ies-inc.local;http://www.*;http://*;https://www.*;https://*;"

As an additional note, weirdly the "UrlAllowList" key was required to make this work on another PC but not my test one. It's probably not required at all but when I added it, it fixed the problem. The user may have not closed the original file or something like that. So just a consideration. I suggest try the least and test it, then add if needed. Once you confirm, you can deploy if needed. Good Luck!

P.S. Another method that worked was mapping the path to the network locally by using mklink /d (symbolic linking in Windows 7 or newer) but mapping a network drive letter (Z: for testing) did not work. Just food for thought and not really recommended. I also did not have to 'Unblock' any files and read probably all the same treads you did and no one had this solution which I thought was odd. Thanks.