Running KDE-4.2.2 Dolphin filemanager as root in Mandriva-2009.1 has been
a problem for me. Today I was playing arround & discovered the following
solution that seems to work well for me & thought I'd share it.

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Create the following executable bash script & save it in your home folder:

Dolphin-helper:
#!/bin/sh

## This script adds user "root" to the list allowed to make connections
## to the X server.

xhost +local:root

Run the following command in konsole as non-root user to add a "link" to the
above script in your ~/.kde4/Autostart folder:

kcmshell4 autostart ..starts "autostart" control module

Restart your computer or logout/login & you should be able to start Dolphin
in root-user mode by typing the following command in (kde cmd-box)
"/usr/bin/krunner":

ALT+F2 ..key combination to start krunner
kdesu dolphin ..start the Dolphin filemanager as root user
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I don't know if starting Dolphin in root-user mode is still a problem in
newer versions of KDE. If the problem still exists, then maybe this
solution can help.