Re enable root login in Ubuntu.
HowTo: First Go to gnome start menu and go to system-->Administration-->User and Groups There search for the user "root".
You will find it. After choosing root, click on "properties" and change the password to something u want. there will be a system generated random root password which you have to erase and set a new one of your choice. once you are done come out of that and close all windows. THEN, again from start menu go to System --> Administration --> Login Screen Setup. There go to the "security" tab and CHECK "allow root to login with GDM". Close all windows and log out of GNOME and on to GDM. type root, root's password that you had set and log in as root! http://ubuntuforums.org/archive/index.php/t-31053.html
alternatieves to root some files:
gksu nautilus in Ubuntu
kdesu konquerer in Kubuntu
gksu thunar in Xubuntu
sudo nautilus works too.