We have a 2003 SBS server and cannot connect to a network share, we get the message, "The specified network name is no longer available". The device is accessible through HTTP, FTP, and from the Windows 7 workstations, but SBS will not connect to the network share. This is true using either net view, \\10.0.0.253 or its network name. We checked that all firewalls are turned off. Symantec End Point Protection is the latest version, 11.0.5002.333, per KB 961293.
No errors are posted in the Event Log.
We have turned off packet signing and encryption for test purposes. The share is on a Buffalo Linkstation Duo.