If you downloaded a local version of the help files, avoid using the
SI_HELP_PROGRAM_ENV environment variable. If you set that environment variable, the browser doesn’t find the help files.
Then, in the General preferences, set Help Location to Local Computer/ Network.
If that doesn’t work, then set Help Location to Custom and use the file:// protocol:
file:///C:\Program Files (x86)\Autodesk\Help\softimage2012\en_us