Duplexing on Headed paper

all users in our company use Windows XP SP2 with Office 2003 SP2/SP3,
everyone has access to a printer to duplex and a colour printer (some are
lucky enough to have an extra printer for all other simplex prints), all of
these printers are networked.

one user complained about a document not being set up correctly and was
printing in the wrong paper tray, after correcting this to print on headed
paper for some reason when they tried printing a duplexed document it came
out on headed paper, but it was upside down and the wrong way round!

i've checked that the paper was in correctly and asked them to try again,
but we got the same results, i compared this to a printer further away in the
office and made sure the paper was in the same way and the settings were
correct, but the outcome didn't change.

we then tried printing a simplex document on headed paper, which strangely
came up the right way round and the right way up. i've been in the page setup
and looked through each of the settings to find a solution, but i'm starting
to lose hope!

it seems a sthough this may be everyones issue rather than just one person!

has anyone got any other ideas?

thanks.