Well, activated static pages.
Added a Static Page using this plugin tab.
Then tried to add a menu item, using the navigation tag.
When adding a Static Page, got a page requesting again for a name and contents.
Gave the same name, but did not fill in the contents.
The Static Page tab still shows my original page, and its contents.
The Navigation tab, shows the page created through the menu edition, without content.
The URL shows an empty page (thus, the one created using the menu edition system).
So, the solution will be, I think (will test now) to move the contents from the custom page plugin page, to the page created when editing the menu. But this needs to be revised.