Since you mentioned that it was working well before you added some new topics, assuming that Printed Documentation output was once created successfully for this project.
Hence the second warning message makes complete sense because your project is updated since you last generated the output.
For the first error message, please share the information about how have you used those newly created topics within RoboHelp; did you link these topics, used them in index, see also or any other such information.
Also let us know about the content of the topics.
I just copied some of the contents and image from a word document. I have used a cover page and some hyperlinks are listed but there is no links to other topics.
but the same thing i was doing it last week as well.. is it problem with the word doc? but i tried generating other test project which i have created before, for those project i could generate 'document' ouput without any issues.. Even i closed all the programmes and restarted the machine...
Please copy paste this content in a topic in fresh project and see if Printed Documentation generates or not.
If the issue persists, can you please share the word file ( source file ) with us.