There is an issue using the HHC.exe with Robohelp v8; the *.hhc (table of contents file) is saved in XML format BUT hhc.exe expects the format to be HTML ... so it cannot process the file and the compiled help (*.chm) file will have no table of contents (and no topics)
I did check the Tools|Options|Convert RoboHelp edited topics to HTML ..... this does not help (in fact seemed to do nothing at all?)
There is another post with this exact issue ... that was never answered (Nov 9 2012)
the exact error message is as described in the other post>>
An internal file could not be created. Make certain there is enough disk space on the drive where you are compiling your file.
Fatal navigational compilation error. This is likely the result of an invalid contents (.hhc) file.
all I need to do is be able to use the HHC.exe which is used in our automated build process ..... so I need to be able to convert (or save) the *.hhc file in HTML format