Open .chm help files over network files
Wednesday, October 07, 2015
Windows Vista and newer have a security setting that stops display of Windows Compiled Help Files, .chm, over a network. Symptom is the table of contents displays on left pane, but contents on right is blank. There may also be an error message of “Navigation to the webpage was canceled.”
Option 1
Copy .chm file to local machine, access file properties and uncheck "Unblock'.
Option 2
Use registry setting to bypass the restriction for named servers.
Allow named server overrides:
REG ADD HKLM\SOFTWARE\Microsoft\HTMLHelp\1.x\ItssRestrictions /v MaxAllowedZone /t REG_DWORD /d 1 /f
Add the named servers to exclusion list (semi-colon delimited list. remove unneeded protocols):
Only UNC shares, of 3 different servers
REG ADD HKLM\SOFTWARE\Microsoft\HTMLHelp\1.x\ItssRestrictions /v UrlAllowList /d ^
“\\yourserver;\\server3;\\server5”
Open web page links to local shares
REG ADD HKLM\SOFTWARE\Microsoft\HTMLHelp\1.x\ItssRestrictions /v UrlAllowList /d ^
“file://\\yourserver;file://\\server3”
Chm hosted on the named web server
REG ADD HKLM\SOFTWARE\Microsoft\HTMLHelp\1.x\ItssRestrictions /v UrlAllowList /d ^
All three: UNC share; link from a web page to local share; web path (.chm files live on web server).
REG ADD HKLM\SOFTWARE\Microsoft\HTMLHelp\1.x\ItssRestrictions /v UrlAllowList /d ^
“\\yourserver;file://\\yourserver;http://your.intranet.web”
Uninstall Option 2
Remove the ItssRestrictions key:
REG delete HKLM\SOFTWARE\Microsoft\HTMLHelp\1.x\ItssRestrictions
From <http://superuser.com/questions/75571/viewing-chm-files-across-the-network-in-windows-7>