I ran into a hard to find but easy to fix issue today on a Windows 2008 R2 DFS server, the namespace suddenly lost all folder targets and displayed as an empty folder. The eventlog showed the following:

Event ID 14534, source DfsSvc: DFS Root xxxxx failed during initialization. The root will not be available.

Additionally, event ID 14503 was logged for each folder target under this namespace.

Solution: remove the server from the namespace, delete the namespace folder on the physical disk and readd the server to the namespace.