I've seem similar posts, and tried a few things from them, but none covered my particular scenario. I'm hoping one of you will have some ideas.
With RoboHelp 9:
Since this problem was occurring and we had struggled with many unrelated problems in the past, support services thought perhaps the best thing to do was uninstall/reinstall RoboHelp 9. They then discovered they no longer had a copy of RoboHelp 9 and upgraded me to RoboHelp 11.
With RoboHelp 11:
Make sure you have all the patches loaded for browser security issues – see Willam’s site (wvanweelden.eu) for a list.