Print preview and printout are different

Question

I have written a program to print out some text and graphics.  When I preview the printout it looks fine and in the center of the page.  However, the printout from the printer is shifted slightly from the center and the right and bottom margin that shows up on my preview is off the page???  (origin at margins is set to false)

I only have one printer to try it on (an HP c5180).  I am really stuck and would appreciate some ideas please.  I can post the code if you wish.

I Think it may be to do with hardmargins but I am not sure

Thanks in advance,
Martyn