Hi there
I think you are mistaken when you say "Nothing has changed". Obviously SOMETHING has changed, no? The question is exactly what. And my guess is that it's the browser that changed via an update. Actually, browser changes have a lot to do with RoboHelp updates. That's why it's a good idea to stay on top of the latest versions of RoboHelp, because they nearly always have new code that allows the RoboHelp output to continue working with new browser versions.
See if the thread linked below helps
Cheers... Rick