Is this only happening on this one project? What happens if you generate one of the supplied sample projects? If it is just this one project, did it ever generate successfully. If so, what has been added since then? Can you generate someother output (e.g. WebHelp) successfully? If not, you'll have to do some detective work to discover what is causing the project to choke.
I had two htm files that I created from a different program. I deleted those files from my project and was able to compile.