Please define *precisely* what you mean by 'slightly offline'.
e.g. is the second invoice print down by one (or how many ) lines?
If so, does same happen on 3rd and 4th invoices, in that the print gradually moves downward in relation to the paper.
Was windows 32 or 64 bit and same on both pc's. If not, I am thinking maybe driver.
Good Luck - Keep us posted.