There are some changes made in xfce-session that are Mandrake specific.

The README of xfce-session states that there are two options with
xfce4-shutdown in xfce-session to reboot/halt the computer.

In Mandrake we use a third option.
Here the console user can execute reboot with help from 
usermode-consoleonly. This package provides /usr/bin/halt,
/usr/bin/reboot and /usr/bin/shutdown, which are the usermode
wrappers for the versions that are available to the root user 
in sbin.
Installing xfce-session from Mandrake will install and use 
usermode-consoleonly.