When you press Help on the toolbar of a MMC snap-in, the Help file does NOT open, and no error message is displayed.
When you attempt to start the MSDN library, you may receive:
Cannot open C:\Program Files\Microsoft Visual Studio\MSDN98\98VSa\1040\msdnv6a.col.
These problems will occur if there is a problem with a tag in the hhcolreg.dat file, used by the HTML Help viewer (Hhctrl.ocx).
To fix this problem:
1. Open a CMD.exe prompt.
2. Type notepad "C:\Documents and Settings\All Users\Application Data\Microsoft\HTML Help\hhcolreg.dat" and press Enter.
2. Locate the <Locations/> XML tag.
3. Replace the <Locations/> XML tag with <Locations> </Locations>.
4. Save the file.
5. Exit Notepad.
6. Exit the CMD prompt.