Issue lost UNC Netbios name search
If you lost the ability to use NetBios system names or DNS functions in SBS 2003 you might have setup your TCP/IP Advanced settings incorrectly.
Check to be sure you have the default NetBIOS settings selected.
Enable LMHOSTS lookup and be sure you have your IP address for your WINS.
Most cases I have seen is the NIC is set to Enable NetBIOS over TCP/IP. If you have issues this might add to them.
Recommended: Set NetBIOS to Default under the WINS tab.