Unable to Connect (Shared Printers in Active Directory)

Environment:
Printers - HP and XEROX
Printers are installed on Windows 2003 Domain Controller
Issues affecting Windows 98, Windows 2000 and Windows XP
Pro clients
All client workstations have static IP

Issue:
We currently have a printing issue with using shared
printers (installed on the Windows 2003 domain
controller) in the
active directory environment. Sporadically, Windows
98/2000/XP Pro workstations will not be able to connect to
the printers (both HP and XEROX). When this happens,
users are still able to access their files on the domain
controller. On the Printers Window, we would see "Unable
to Connect" on the status column. Sometimes, if the users
wait a while, they will be able to print again. If I
asked them to log off and back on, they would not be able
to print. If I asked them to restart, they would be able
to print right away.