enable root login

Login with default user and type

>>>>>$ sudo su
It will ask for password give password and you are now root user check the shell prompt(#)
Now type
>>>>># passwd
And enter new password for root , confirm it by typing once again
Now your password for root is set
Now open
System > Administration > Login Window
Go for Security tab
Check the box with option Allow system Administrator login
Done
you can do root login

You can play with some more options there like automatic login and Timed login
Enjoy !