We've got a LaserJet 4100 that refuses to collate, at least with the PS
driver (most of our printing is PDFs). The appropriate M$ patches are
installed, and the user can send jobs to other model printers and they
collate. They simply don't collate going to the 4100. Does anyone have
suggestions for this? Do you think a newer iPrint client might help (the
one we're running is fairly old)?

Windows XP SP2 with kb884897 and kb893225
iPrint client 4.16