Workstations can't access other workstation shared printers

We have a Small Business Server 2003 domain with XP pro workstations.
Everyone logs in to their respective workstations using domain\username.
When browsing the network, users can see other workstations on the network
places list, but can't access shared printers or shares.

When I try to add domain\users to the workstation users, it says, "The trust
relationship between this workstation and the primary domain failed." Don't
know if that's related to the problem. (Even when logged in at the
workstation as the domain admin.)

What steps are required to give domain users access to other domain user's
printers?