Logging into the Management Console returns the error: Multiple connections to CoreName using more than one user name are not allowed. Disconnect all previous connections. (User Authentication Error 1219).
A connection using different authentication credentials has already been created with the Core Server.
Disconnect mapped drive to core server.
Re-open the console.
Ensure that Consoles have the latest service pack applied.
Also, reboot the client machine containing the remote console if necessary.
If the first resolution does not work put in the FDQN for the core server into the core option on the login screen.