I cannot open Help files that require the Windows Help (WinHlp32.exe) program
On computers that are running Windows Vista or Windows Server 2008, you may be unable to open Help files that require the Windows Help (WinHlp32.exe) program. This article provides information about a download that helps you fix this problem.
Ever since Windows 3.1, Microsoft included the Windows Help program (WinHlp32.exe) with new releases. WinHlp32.exe is used to view 32-bit Help files that have the .hlp file name extension. Starting with the release of Windows Vista and Windows Server 2008, Microsoft has decided to no longer include in WinHlp32.exe as a component of the Windows operating system. Microsoft made this decision because WinHlp32.exe has not had a major update for many years, and it does not meet our standards for all new Microsoft programs. Microsoft realizes that this may cause some difficulties for customers who want to upgrade to Windows Vista or to Windows Server 2008 but still rely on 32-bit .hlp files. Therefore, Microsoft is making WinHlp32.exe available as a download from the Microsoft Download Center.
Special note for Help content providers who ship .hlp files
Starting with the release of Windows Vista and Windows Server 2008, third-party software developers are no longer authorized to redistribute WinHlp32.exe with their programs. For more information, see the “More information for Help content providers who are shipping .hlp files” section.
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB917607.