Version:            (using KDE KDE 3.5.4)
Installed from:    Ubuntu Packages
Compiler:          gcc version 4.0.3 (Ubuntu 4.0.3-1ubuntu5) 
OS:                Linux

This is similar to bug 56006 and may be related.  The screensaver pick list in kcontrol and systemsettings has no entries despite the fact that the screensavers are installed and actually working.  But there is no crash when the "default" button is pressed.  In fact, I see no error output relating to it at all when running kcontrol from a terminal.  It's been going on for a few versions of KDE, since at least 3.5.0.  
I've recently found that this bug is related to the file ~/.config/menus/applications-kmenuedit.menu.  If I move that file and long in, the screensaver pick list works normally.  I don't see anything wrong with this file, or how it relates to the screensaver control panel.  Nothing else at all seems to be affected by it (other than the kmenu).
The file has never been modified by any means other than kmenuedit to the best of my knowlege.  From kcontrol's output, it seems to be getting confused with all those System-n entries and where to find the screensavers.  There is no ScreenSaver entry in the K menu that I can find.

Here is the output from running kcontrol in a terminal:

kcontrol
kio (KSycoca): Trying to open ksycoca from /var/tmp/kdecache-moir9D0ERf/ksycoca
kcontrol: Found basegroup = Settings/
kcontrol: relPath=System-5/ScreenSavers/
ScimInputContextPlugin()

Here is the contents of my applications-kmenuedit.menu:

<!DOCTYPE Menu PUBLIC "-//freedesktop//DTD Menu 1.0//EN" "http://www.freedesktop.org/standards/menu-spec/1.0/menu.dtd">
<Menu>
 <Include>
  <Filename>kde-Kfind.desktop</Filename>
 </Include>
 <Menu>
  <Name>Internet</Name>
  <Include>
   <Filename>Firefox.desktop</Filename>
   <Filename>KMail.desktop</Filename>
   <Filename>AEJAVA.desktop</Filename>
  </Include>
  <Layout>
   <Merge type="files" />
   <Filename>kde-Apollon.desktop</Filename>
   <Filename>kde-ktorrent.desktop</Filename>
   <Filename>kde-kget.desktop</Filename>
   <Filename>kde-ksirc.desktop</Filename>
   <Filename>kde-ksniffer.desktop</Filename>
   <Filename>AEJAVA.desktop</Filename>
   <Filename>Firefox.desktop</Filename>
   <Merge type="menus" />
   <Menuname>Terminal</Menuname>
   <Filename>kde-krfb.desktop</Filename>
   <Filename>kde-kopete.desktop</Filename>
   <Filename>kde-Kppp.desktop</Filename>
   <Filename>KMail.desktop</Filename>
   <Filename>gaim.desktop</Filename>
   <Filename>kde-krdc.desktop</Filename>
   <Filename>kde-akregator.desktop</Filename>
   <Filename>firefox.desktop</Filename>
   <Filename>kde-konqbrowser.desktop</Filename>
   <Filename>kde-kwifimanager.desktop</Filename>
   <Filename>xchat.desktop</Filename>
   <Separator/>
   <Menuname>More</Menuname>
  </Layout>
 </Menu>
 <Exclude>
  <Filename>Firefox.desktop</Filename>
 </Exclude>
 <Menu>
  <Name>Games</Name>
  <Include>
   <Filename>Return to Castle Wolfenstien.desktop</Filename>
   <Filename>kde-JFDuke3D.desktop</Filename>
   <Filename>kde-Play Grim Fandango.desktop</Filename>
  </Include>
  <Menu>
   <Name>JFDuke3D</Name>
   <Include>
    <Filename>kde-Game Data Installer.desktop</Filename>
    <Filename>kde-Setup.desktop</Filename>
   </Include>
   <Exclude>
    <Filename>kde-JFDuke3D.desktop</Filename>
   </Exclude>
   <Deleted/>
  </Menu>
  <Layout>
   <Merge type="files" />
   <Filename>kde-Play Grim Fandango.desktop</Filename>
   <Filename>kde-JFDuke3D.desktop</Filename>
   <Filename>Return to Castle Wolfenstien.desktop</Filename>
   <Merge type="menus" />
   <Menuname>Toys</Menuname>
   <Menuname>Arcade</Menuname>
   <Menuname>Board</Menuname>
   <Menuname>Card</Menuname>
   <Menuname>Kidsgames</Menuname>
   <Menuname>TacticStrategy</Menuname>
  </Layout>
 </Menu>
 <Menu>
  <Name>Office</Name>
  <Menu>
   <Name>Electronics</Name>
   <Directory>Electronics.directory</Directory>
  </Menu>
  <Layout>
   <Merge type="files" />
   <Filename>Autocad R14.desktop</Filename>
   <Filename>kde-Kontact.desktop</Filename>
   <Separator/>
   <Filename>ooo2-base.desktop</Filename>
   <Filename>ooo2-calc.desktop</Filename>
   <Filename>ooo2-draw.desktop</Filename>
   <Filename>ooo2-impress.desktop</Filename>
   <Filename>ooo2-math.desktop</Filename>
   <Filename>ooo2-writer.desktop</Filename>
   <Filename>template.desktop</Filename>
   <Filename>AdobeReader.desktop</Filename>
   <Separator/>
   <Merge type="menus" />
   <Menuname>More</Menuname>
  </Layout>
  <Include>
   <Filename>Autocad R14.desktop</Filename>
  </Include>
 </Menu>
 <Menu>
  <Name>Applications</Name>
  <Menu>
   <Name>Electronics</Name>
   <NotDeleted/>
  </Menu>
  <Layout/>
  <Exclude>
   <Filename>wine.desktop</Filename>
  </Exclude>
 </Menu>
 <Menu>
  <Name>Electronics</Name>
  <NotDeleted/>
  <Include>
   <Filename>Circad.desktop</Filename>
   <Filename>Circuit Maker.desktop</Filename>
  </Include>
  <Layout>
   <Merge type="files" />
   <Filename>Circuit Maker.desktop</Filename>
   <Filename>Circad.desktop</Filename>
  </Layout>
  <Menu>
   <Name>System</Name>
   <NotDeleted/>
  </Menu>
 </Menu>
 <Move>
  <Old>Office/Electronics</Old>
  <New>Electronics</New>
 </Move>
 <Move>
  <Old>Electronics</Old>
  <New>Applications/Electronics</New>
 </Move>
 <Move>
  <Old>Applications/Electronics</Old>
  <New>Electronics</New>
 </Move>
 <Menu>
  <Name>Graphics</Name>
  <Include>
   <Filename>Picasa.desktop</Filename>
  </Include>
  <Layout>
   <Merge type="files" />
   <Filename>qcad.desktop</Filename>
   <Filename>gimp-2.2.desktop</Filename>
   <Filename>kde-krita.desktop</Filename>
   <Filename>Picasa.desktop</Filename>
   <Filename>kde-gwenview.desktop</Filename>
   <Filename>kde-kpdf.desktop</Filename>
   <Filename>kde-ksnapshot.desktop</Filename>
   <Separator/>
   <Merge type="menus" />
   <Menuname>More</Menuname>
  </Layout>
  <Exclude>
   <Filename>xsane.desktop</Filename>
   <Filename>kde-kooka.desktop</Filename>
  </Exclude>
 </Menu>
 <Menu>
  <Name>Wine</Name>
  <Menu>
   <Name>Programs</Name>
   <Menu>
    <Name>JFDuke3D</Name>
    <Include>
     <Filename>kde-JFDuke3D.desktop</Filename>
    </Include>
   </Menu>
   <Menu>
    <Name>LucasArts</Name>
    <Menu>
     <Name>Grim Fandango</Name>
     <Include/>
     <Layout/>
     <Exclude>
      <Filename>kde-Play Grim Fandango.desktop</Filename>
     </Exclude>
    </Menu>
   </Menu>
  </Menu>
  <Layout>
   <Merge type="menus" />
   <Menuname>Programs</Menuname>
  </Layout>
  <Menu>
   <Name>System</Name>
   <NotDeleted/>
  </Menu>
 </Menu>
 <Move>
  <Old>Wine/Programs/JFDuke3D</Old>
  <New>Games/JFDuke3D</New>
 </Move>
 <Menu>
  <Name>System</Name>
  <Layout>
   <Merge type="menus" />
   <Menuname>Terminal</Menuname>
   <Merge type="files" />
   <Filename>kde-k3bsetup2.desktop</Filename>
   <Filename>kde-kinfocenter.desktop</Filename>
   <Filename>Konqueror.desktop</Filename>
   <Filename>language-selector.desktop</Filename>
   <Filename>smeg-kde.desktop</Filename>
   <Filename>NVIDIA-Settings.desktop</Filename>
   <Filename>synaptic-kde.desktop</Filename>
   <Filename>kde-ksysguard.desktop</Filename>
   <Filename>kde-ksystemlog.desktop</Filename>
   <Filename>kde-kcron.desktop</Filename>
   <Filename>kde-konsole.desktop</Filename>
   <Filename>kde-kuser.desktop</Filename>
   <Separator/>
   <Menuname>More</Menuname>
  </Layout>
  <Menu>
   <Name>Terminal</Name>
   <Layout/>
   <Include/>
   <Exclude>
    <Filename>Konqueror.desktop</Filename>
   </Exclude>
  </Menu>
  <Include>
   <Filename>Konqueror.desktop</Filename>
  </Include>
 </Menu>
 <Menu>
  <Name>Utilities</Name>
  <Menu>
   <Name>Settingsmenu</Name>
   <NotDeleted/>
   <Menu>
    <Name>File</Name>
    <NotDeleted/>
   </Menu>
   <Layout/>
   <Exclude>
    <Filename>language-selector.desktop</Filename>
   </Exclude>
  </Menu>
  <Move>
   <Old>File</Old>
   <New>Settingsmenu/File</New>
  </Move>
  <Menu>
   <Name>File</Name>
   <NotDeleted/>
  </Menu>
  <Move>
   <Old>Settingsmenu/File</Old>
   <New>File</New>
  </Move>
  <Menu>
   <Name>Editors</Name>
   <NotDeleted/>
  </Menu>
  <Menu>
   <Name>System</Name>
   <NotDeleted/>
   <Include/>
   <Layout>
    <Merge type="menus" />
    <Menuname>Terminal</Menuname>
    <Merge type="files" />
    <Filename>kde-k3bsetup2.desktop</Filename>
    <Filename>kde-kinfocenter.desktop</Filename>
    <Filename>Konqueror.desktop</Filename>
    <Filename>language-selector.desktop</Filename>
    <Filename>smeg-kde.desktop</Filename>
    <Filename>NVIDIA-Settings.desktop</Filename>
    <Filename>synaptic-kde.desktop</Filename>
    <Filename>kde-ksysguard.desktop</Filename>
    <Filename>kde-ksystemlog.desktop</Filename>
    <Filename>kde-kcron.desktop</Filename>
    <Filename>kde-konsole.desktop</Filename>
    <Filename>kde-kuser.desktop</Filename>
    <Separator/>
    <Menuname>More</Menuname>
   </Layout>
   <Exclude>
    <Filename>wine.desktop</Filename>
   </Exclude>
  </Menu>
  <Include>
   <Filename>wine.desktop</Filename>
  </Include>
  <Exclude/>
  <Layout>
   <Merge type="menus" />
   <Menuname>File</Menuname>
   <Menuname>Editors</Menuname>
   <Menuname>Settingsmenu</Menuname>
   <Menuname>XUtilities</Menuname>
   <Merge type="files" />
   <Filename>kde-kate.desktop</Filename>
   <Filename>kde-ark.desktop</Filename>
   <Filename>kde-groupwarewizard.desktop</Filename>
   <Filename>kde-karm.desktop</Filename>
   <Filename>kde-knotes.desktop</Filename>
   <Filename>kde-konserve.desktop</Filename>
   <Filename>speedcrunch.desktop</Filename>
   <Filename>wine.desktop</Filename>
   <Filename>emacs21.desktop</Filename>
   <Filename>kde-katapult.desktop</Filename>
   <Separator/>
   <Menuname>More</Menuname>
  </Layout>
  <Menu>
   <Name>System-2</Name>
   <NotDeleted/>
  </Menu>
  <Move>
   <Old>System</Old>
   <New>System-2</New>
  </Move>
 </Menu>
 <Move>
  <Old>Settingsmenu</Old>
  <New>Utilities/Settingsmenu</New>
 </Move>
 <Menu>
  <Name>.hidden</Name>
  <Include>
   <Filename>xsane.desktop</Filename>
   <Filename>kde-kooka.desktop</Filename>
   <Filename>language-selector.desktop</Filename>
  </Include>
 </Menu>
 <Move>
  <Old>System</Old>
  <New>Utilities/System</New>
 </Move>
 <Menu>
  <Name>Mechanical</Name>
  <Directory>Mechanical.directory</Directory>
  <NotDeleted/>
  <Include>
   <Filename>Torque Calculator.desktop</Filename>
  </Include>
  <Layout>
   <Merge type="files" />
   <Filename>Torque Calculator.desktop</Filename>
  </Layout>
  <Menu>
   <Name>System</Name>
   <NotDeleted/>
  </Menu>
 </Menu>
 <Menu>
  <Name>System-2</Name>
  <NotDeleted/>
 </Menu>
 <Move>
  <Old>Utilities/System-2</Old>
  <New>System-2</New>
 </Move>
 <Menu>
  <Name>Debian</Name>
  <Layout/>
  <Menu>
   <Name>System</Name>
   <NotDeleted/>
  </Menu>
 </Menu>
 <Menu>
  <Name>Edutainment</Name>
  <Layout>
   <Merge type="menus" />
   <Menuname>Languages</Menuname>
   <Menuname>Mathematics</Menuname>
   <Menuname>Miscellaneous</Menuname>
   <Menuname>Science</Menuname>
   <Menuname>Tools</Menuname>
  </Layout>
  <Menu>
   <Name>System</Name>
   <NotDeleted/>
  </Menu>
 </Menu>
 <Menu>
  <Name>System-3</Name>
  <NotDeleted/>
 </Menu>
 <Move>
  <Old>System-2</Old>
  <New>System-3</New>
 </Move>
 <Move>
  <Old>System-3</Old>
  <New>Mechanical/System</New>
 </Move>
 <Move>
  <Old>Mechanical/System</Old>
  <New>Electronics/System</New>
 </Move>
 <Move>
  <Old>Electronics/System</Old>
  <New>Wine/System</New>
 </Move>
 <Move>
  <Old>Wine/System</Old>
  <New>Debian/System</New>
 </Move>
 <Move>
  <Old>Debian/System</Old>
  <New>Edutainment/System</New>
 </Move>
 <Move>
  <Old>Edutainment/System</Old>
  <New>System-3</New>
 </Move>
 <Menu>
  <Name>Mechanical-2</Name>
  <NotDeleted/>
 </Menu>
 <Move>
  <Old>Mechanical</Old>
  <New>Mechanical-2</New>
 </Move>
 <Menu>
  <Name>System-4</Name>
  <NotDeleted/>
 </Menu>
 <Move>
  <Old>Utilities/System</Old>
  <New>System-4</New>
 </Move>
 <Layout>
  <Merge type="menus" />
  <Menuname>Wine</Menuname>
  <Menuname>Debian</Menuname>
  <Menuname>Development</Menuname>
  <Menuname>System-3</Menuname>
  <Menuname>Edutainment</Menuname>
  <Menuname>Games</Menuname>
  <Menuname>Graphics</Menuname>
  <Menuname>Internet</Menuname>
  <Menuname>Multimedia</Menuname>
  <Menuname>Office</Menuname>
  <Menuname>Science</Menuname>
  <Menuname>System-5</Menuname>
  <Menuname>Utilities</Menuname>
  <Menuname>Applications</Menuname>
  <Menuname>Mechanical-2</Menuname>
  <Menuname>Electronics</Menuname>
  <Merge type="files" />
  <Filename>kde-Help.desktop</Filename>
  <Filename>kde-Kfind.desktop</Filename>
  <Filename>kde-systemsettings.desktop</Filename>
 </Layout>
 <Menu>
  <Name>Science</Name>
  <Layout/>
  <Menu>
   <Name>System</Name>
   <NotDeleted/>
  </Menu>
 </Menu>
 <Move>
  <Old>System-4</Old>
  <New>Science/System</New>
 </Move>
 <Menu>
  <Name>System-5</Name>
  <NotDeleted/>
 </Menu>
 <Move>
  <Old>Science/System</Old>
  <New>System-5</New>
 </Move>
</Menu>

Thank you for your time and efforts.  I do hope this is actually a bug and not just an ungraceful error caused by an erroneous applications-kmenuedit.menu