maybe, you just lost the entry to the mandrake control center (mcc) in your (kde/gnome) menu somehow.
you can (re)create an entry for the mcc by right-clicking on the menu-button. then choose edit menu. now mandrake linux menu editor opens and you can choose where you want to recreat the entry (new program button on the top). default, as you said system/configuration. the path to mcc is /usr/sbin/drakconf.
you can also start the mcc in console, by becoming root and typing mcc in the command line.