I'm having the same issue with one of my RoboHelp 8 projects
when I initially tried to open the project. I renamed the .cpd file and am able to work without the message appearing.
However, one of the many times when I got the "RoboHelp has to close" error, my
table of contents, index, and glossary files were emptied. They're still there, but there's no content.
Do you think this is a separate issue, or something related?
Sounds like at that point, you've got a damaged project. Killing the .cpd database may help, but you may be forced to use a backup or start repairing the project as is. You should be looking at solving the "...one of many times when..." issue though - RH shouldn't be crashing on you.