Theme North, Oops! That page can’t be found. Home page and navigation.

Whilst working on my home page, after creating dummy pages in order to place the menu, I find that when I try to navigate via the menu to the other page I get the “Oops! That page can’t be found.” message. I’m being forced by the interface to edit my home page on the Custom Home Page and I don’t know why my pages are no longer found. Any suggestions, please? I am working on a WordPress multisite installation.