When opening a Rich Text Format (.RTF) format document in Wordpad the following error is reported, and content does not display correctly.

"This document contains code that your security settings do not allow, so it might not display correctly"

Compiled HTML Help (.CHM) files come up with the following messages in the left pane:

"Navigation to the webpage was canceled"
"This program cannot display the webpage"

Set the following registry key to resolve the issue.

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap\ProtocolDefaults]
"file"=dword:00000000

For Windows Server 2008/Vista ownership must be taken of the registry key first. From regedit:

- Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap\ProtocolDefaults
- Right click on ProtocolDefaults and select Permissions from the context menu
- Click Advanced
- Select the Owner tab
- Select a suitable account (Administrators) and click OK
- Select the appropriate group (Administrators)and check the Full Control checkbox
- Click OK
- Double click on file in the right pane
- Enter the value 0 and click OK

Setting the UNCAsIntranet may also be required

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap]
"UNCAsIntranet"=dword:00000001

For Compiled HTML Help files additional registry entries may be required to allow access to the InfoTech protocol. e.g

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\HTMLHelp\1.x\ItssRestrictions]
"MaxAllowedZone"=dword:00000001

Also files downloaded from the Internet may need to be unblocked from Attachment Manager:

- Right-click the blocked file, and then click Properties.
- In the General tab, click Unblock.

You cannot open remote content by using the InfoTech protocol after you install security update 896358, security update 840315, or Windows Server 2003 Service Pack 1
http://support.microsoft.com/kb/896054

You cannot open HTML Help files from Internet Explorer after you install security update 896358 or Windows Server 2003 Service Pack 1
http://support.microsoft.com/kb/902225

Certain Web sites and HTML Help features may not work after you install security update 896358 or security update 890175
http://support.microsoft.com/kb/892675

MS05-026: A vulnerability in HTML Help could allow remote code execution
http://support.microsoft.com/kb/896358

"Windows has blocked access to these files to help protect your computer" when extracting a .ZIP file
http://theether.net/kb/100023