"Network name no longer available"

If you try to copy large files between a Windows Server 2003/ 2008 host and a VMWare Server guest (on the same physical server) you may see this error in the VM with the copy failing. On the host you will see a 2025 event in the System log indicating a DOS attack:

Event Type: Warning
Event Source: Srv
Event Category: None
Event ID: 2025
Date: 1/14/2009
Time: 3:42:57 PM
User: N/A
Computer:
Description:
The server has detected an attempted Denial-Of-Service attack from client \\10.x.x.x, and has disconnected the connection.

To get around this you need to disable DOS protection on the host server. Open regedit and navigate to HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\LanManServer\Parameters
Add a DWORD value named DisableDos with a value of 1 to enable it. Reboot the host server.