This is a long shot, but it may be the quotation marks themselves.
Word 2007 inserts straight quotation marks in index fields, even when curly quotes are being automatically applied during typing. RoboHelp should be translating the straight quotes as "code" and removing them during index import.
Is there any chance that your index fields got curly quoted by mistake? Because it looks like RH is translating the quotes as characters.
After reading this response, I checked the index entries in the Word document. Since the document was created from an original RoboHelp 3X project, I thought I would not find curly quotes. What I found was this:
(1) Some portions of the index entry had straight quotes - these portions were imported from the old RoboHelp into an old Word document that I reused.
(2) Some portions of the index entry had curly quotes - these portions were added manually by me after turning on Tools->Options->Formatting Marks->View All and then manually adding index entries.
Any attempts to make the curly quotes straight were not successful. Then I found an AutoCorrect setting that was checked that stated "Replace straight quotes with smart quotes". When I unchecked that, all newly entered quotes show as straight and NOT curly. I then did a global find and replace with the index formatting marks enabled for view to change all quotes from curly to straight.
I then tested the source Word document with the import in RoboHelp and IT WORKED!!!!!
Thanks Elisa ---