On our LAN of about 30 workstations, we lost the ability to access the server (Shared Folders) with simply typing in \\SERVERNAME in the Explorer. I can still access the server by its IP address, but all of the network settings (backups on workstations, printers, scanners) are configured to access it by its server name. The only thing that was changed is our switch for small part of the network (upgraded to Netgear Gigabit switch). The switch connects 10 workstations to the main Gigabit switch. I don't see how it can be Switch's fault - it seems to operate well.
Not sure, but Windows2003 might of downloaded some updates recently and restarted the server on its own.
Observation: Some workstations are still able to access the server by it's name: \\servername , these are desktops and some laptops that weren't removed from the office, the problem seems to only occur with laptops that are taken home and disconnected from network.
Here's our set-up:
We have 1 Windows 2003R2 server that has SharedFolders on it, workgroup, and also has Kerio WinRoute Firewall installed - the KWF software acts as a Firewall/DHCP/VPN server.