CorelDRAW X6 :: Opening Files From Other Versions?

In CorelDraw files, the color palette varies from one artist to another based presumably on the version of Corel. If one artist opens another artists files, some of the color (mostly black) appear as clear/white/invisible. Colors appear normally, however, for the artist to whom the file belongs.This may be also related to an issue with "black boxes". An artist opens an old color separation file or a color separation file created by another artist, and the color separation dialog tab in the print dialog shows multiple check boxes for "undefined" colors. These print out as blank color separations regardless of whether the box is unchecked.If all of the art is selected on the page, cut and pasted to a new page and the old page deleted, the undefined black boxes cease to exist.