Using RH2015 and MS Word 2010.
[Version of RoboHelp edited by Moderator. Please always use the correct version name as it helps people with the same problem down the line find a post that may help them. In this case it was referred to as RH15 so a search on RH15 would fail.]
Using Master pages, more or less from the RH15 EmployeeCare3 sample project.
I created a new project, imported about 15 pages from that project and modified them to be specific to my project (shared with a half dozen other writers who lack RH experience).
I noted that the header.footer had additional paragraph marks, which took up additional space in the printed document..
I saw that the paragraph styles for the header were undefined, so I changed the paragraph style to "header" and set the above/below space to 0.
This made the topic body content disappear completely -- and then I recived the title as an error:
Unhandled win32 exception occurred in RoboHTML.exe 
First please note for future reference the edit I made to your post. It helps others if you correctly refer to RoboHelp 2015 rather than 15.
I don't think Word 2010 is compatible with this version of RoboHelp but I can't see any link with this problem and Word. Have I missed something there?
Try changing the style to Normal to see if that stops the error. Also try using the master page from the sample project without making any changes. Does either of those ideas stop the crash?
See www.grainge.org for RoboHelp and Authoring information