Comment 7 for bug 58898

 Jérôme: your description of choosing landscape sounds like a 1.6.x or early 1.7x version of Gnumeric. In those versions printing in landscape was a gamble that usually did not pay off.

In recent versions 1.7.x (I think 1.7.10 and later), to print landscape:

select page-setup
click on "Change paper type"
this opens a second dialog in which you can choose the orientation via radio buttons.

In these recent versions of Gnumeric the landscape printing trouble should be gone! (If it isn't, let me know and it will be a priority to fix it.)