Fatal Error: Unexpected error from Microsoft HTML Compiler. Finished compiling HTMLHELP in175 sec(s)

I'm working in RoboHelp v7 and when I go to generate my CHM Files to a folder on my D Drive I get the above Fatal Error.

I have recreated the folder and path where the generated CHM files are to be created and this seemed to fix the problem for one publish, but now it is back.

I have found a work around which allows me to publish which is removing some spaces from the file name of the CHM files that are generated.

Any help is muchly appreciated even though I have a work around I still need to find a solution to this problem.

Thanks,

Kristy