Shared printer and windows xp service pack 3

Hello,

I have a HP Deskject 5550, attached via USB to a windows xp SP2 PC (host),
and shared using a hidden network share (like \\pc\share$).

Another PC (guest), using windows XP sp2 used this share for more than a
year now, printing with no issues at all.

A few hours ago I have installed SP3 of winodws XP (including reboot) on the
guest PC and now it can't print to the shared printer.
Locally, on the host PC (still SP2...) - printing is continuing to work fine.

When opening the printer from the guest PC - it is OK, online and no "access
denied" message.
When printing to it nothing happens. when printing a printer test page I get
the message "test page failed to print" and no document is added to the
printing queue.

I tried to remove the printer from the guest PC and also delete the drivers
and then install it again via the network - but all the same.

It looks like SP3 messed things up here.

Do you have any idea of this and how to solve this?

Thanks.

Eitan