Sadly, RoboHelp 9 is three versions old. The WebHelp output is likely having problems functioning correctly in today's modern browsers.
You seriously need to consider downloading the eval of the latest RoboHelp (2015 Release) and testing from that.
Rick is correct. But until your new RH2015 arrives, you could try removing the eHlpDhtm.js from your source and regenerating. That helped (somewhat) for me.
Thank you for your responses and so quickly. I was wondering if it was a version problem.