The configuration info for your screensaver in kde is in /home/<username>/.kde/share/config/kdesktop.rc. However, if you login to kde you probably won't have enough time to get at the file. To get around this dilema, boot into a non-graphical, command line login(run level 3) by rebooting and hitting the Esc key as soon as you see the lilo selection screen. This will take you to a boot prompt at which you type:
You will then boot to a command line login where you should login with your usual user name and password. At the prompt, run:
$ mv /home/<username>/.kde/share/config/kdesktop.rc /home/<username>/.kde/share/config/old.kdesktop.rc
and reboot. You will lose all your desktop settings but the screensaver should be reset to the default condition, i.e. kde automatically recreates a new kdesktop.rc using the default settings. From there you can either redo your settings in kcontrol or try hand editing the "ScreenSaver" section in old.kdesktop.rc toward the end of the file.