Samba Error-WindowsXP Shares-(Error NT_STATUS_UNSUCCESSFUL)

Question

john@Laptop:~$ smbtree
Enter john's password: 
MYHOME
    \\LAPTOP                Laptop server (Samba, Ubuntu)
        \\LAPTOP\print$         Printer Drivers
        \\LAPTOP\John           Lubuntu-Laptop-Home
        \\LAPTOP\IPC$           IPC Service (Laptop server (Samba, Ubuntu))
    \\DESKTOP               
john@Laptop:~$ smbclient -L Desktop -U John
Enter Jim's password: 
Connection to Desktop failed (Error NT_STATUS_UNSUCCESSFUL)

But when I substitute smbclient -L Desktop -U John with smbclient -L ip.address. -U John instantly it shows all the shares.

I am using Lubuntu 12.10. When I try to connect using GUI (File Manager-Network Connections), it doesn't connect and says timeout.

Please help me solve this guys. Thanks