What are you printing from Dan; Lightroom, Photoshop, Qimage? Other?
... Qimage can mess you up, thinking you've deleted or zero'd out margins.
It's a long time since I had the Z3100 so I don't recall the driver page but my Epson driver recently turned on a magnification/reduction setting on it's Page Layout screen that had me baffled for a while (even with Page Size set correctly).