Per this Microsoft KB: http://support.microsoft.com/kb/938120
Use one of the following methods to workaround this behavior (method 1 and 2 come from the above Microsoft article):
Method 1
Use the IP address of the remote server when you try to connect to the network share.
Method 2
Create a different Domain Name System (DNS) alias for the remote server, and then use this alias to connect to the network share.
After you use one of these methods, you can use different user credentials to connect to the network share. In this situation, the computer behaves as if it is connecting to a different server.
Additionally a third method may allow for the existing server name to be added in Rapid Recovery.
Method 3
1) From an administrative command prompt type Net Use, and note the active connections and any that relate to the storage path that is required to be added (eg. \\servername\sharename)
2) Type net use \\servername\sharename /delete and confirm the connection is removed by running net use again and noting the active connections
3) In services.msc restart both the Server and Workstation services
4) Attempt adding the UNC path again in the Core GUI
