What's the error number (if there is one, google that. it'll usually help). If this is a compiler dialogue box, then I'm not sure. If you're using multiple compilers that may cause it to say such a thing.
One thing you can do, copy the whole code, open a new instance of vc, and open a new plain text doc with the little button that does those instead of file-open and using the menu. Paste and then save as .cpp. See if that works. Then vc can't build a module (which is basically predetermined code) so it shouldn't have to worry about it.
No, that's not "what the button did anyway". The button deletes all output files keeping only the original files you had, and remakes them from scratch.