I have never had a problem with the update system.
There's one thing I need to clear up for you regarding root privileges:
su: Permanent root log in through terminal
sudo: Temporary root log in for command line programs
kdesu: Temporary root log in for graphical programs.
For the command 'dpkg --configure', you would use 'sudo' because it's a command line program.
You'd only use 'kdesu' to launch a graphical program like Kate, with root privileges
As for your problem, try 'sudo dpkg -configure' (one line, not two) or 'dpkg --help'