ms word 2003 prints blank pages when using pages-per-sheet option

our network printers behave a little bit strange when users print from
microsoft word 2003. when a user prints more pages per sheet using the word's
built-in zoom option (accessible from the print dialogue), the printer
sometimes prints blank page, sometimes the printed text is shrinked to 5% of
its original size.
this error occurs randomly and usualy when a user tries to print the
document again, it's printed correctly.
we tried all existing drivers but it didn't help.

using the pages-per-sheet option in driver's properties works well.
anyone knows what's the problem and how to solve it?