If a domain's Distributed File System (DFS) root server is unavailable, a client computer that is running Windows Vista cannot connect to another DFS server that is listed in the referral when the client computer tries to connect to the DFS root server. DFS failover does not occur. When the client computer tries to connect to the offline DFS server, you receive an error message that resembles the following:
System error 1214 has occurred. The format of the specified network name is invalid.
Install this update to resolve the issue.
Windows Vista, Microsoft, DFS, Update