RoboHelp 8 - Broken links on opening a project

I am on RoboHelp8 and have been using the software for a couple of months and now suddenly am getting this error on just one project -- the main project. I called RoboHelp support and they said that they don't support file specific issues. Can anyone please help me with this error? Before the error comes up, when I open the project, many messages come up first that say "The hyperlink "whatever.htm" used in "topic.htm", is outside of the current project and will not be shown in Project Manager". This message is coming up for many topics - seems like something has happened with the hyperlinks for this particular project. After these messages the Runtime Error comes up. I am relatively new user of RoboHelp and the person who worked on this before is no longer with the company and was using RoboHelp 5 (the upgrade from 5 to 8 caused other issues, but not this one). Any help would be greatly appreciated! Thanks.