You have to change the computers hostname & hosts files.
- Open a terminal window using following shortcut keys “ctrl+alt+t”
- Edit the hostname file and replace the name
- gksudo gedit /etc/hostname
- When prompted, enter the administrator password and click the OK button.
- The hostname file will open, displaying the current computer name. Replace the current computer name with the desired new name.
- Click Save.
- also change the name in hosts
- gksudo gedit /etc/hosts
- Leave the other stuff there untouched.
Close all open windows and restart your system.