Auto print offsets pages

I'm using PDFcreator as default printer, saving to PDF and making an automatic hardcopy on a physical printer.

The PDF files look OK, exact match of what I would get by printing directly. The paper output however is offset, cutting off about 1 cm of the page at the bottom and leaving an extra 1 cm of white space at the top (printing in landscape). The size of the print is fine (printing in landscape, from custom application - no options for margins or paper size). Any suggestions?

Many thanks