You need to make some changes to get your 3.0 Help file to compile under Windows Help version 3.1.
To prepare a 3.0 source file for compiling under version 3.1
1.1.Change INDEX= to CONTENTS= in the Help project file.
2.2.Change side-by-side paragraphs (if any) to tables.
3.3.Check to make sure there are no hidden paragraph marks or hidden page breaks.
For more information about the CONTENTS option, see Chapter 16, “The Help Project File.” For more information about creating tables, see Chapter 7, “Formatting Topics.”