I'm on Maverick trying to access shared folders hosted on Windows machines across a home network. Mysteriously I stopped being able to see them through Nautilus (I couldn't even open Windows network and see my own machine), nor using "smbclient -L //HOSTNAME" from the command line. The error code I got was NT_STATUS_UNSUCCESSFUL.
I discovered the problem was I had recently started using OpenDNS and Samba resolves local hostnames using DNS. Of course, OpenDNS can't resolve my local network hostnames.
The solution is to edit your Samba configuration so that the hostnames are resolved locally and then restart Samba: