After applying Service Pack II to your Windows Server 2003 Print server, printers start showing offline alltough they where online prior to installing SPII.
The problem is caused because SNMP is dissabled on the printer device. You have to enable this setting or disable the SNMP check on your logical printer (printer on server). You can dissable SNMP on the port configuration tab of your printer.
It can also happen that offline printers show online, this means SNMP is enabled on the printer device.