If you can reproduce the crash at will, may you read http://techbase.kde.org/Development/Tutorials/Debugging/How_to_create_useful_crash_reports and post a complete backtrace here? 
You may need to install "kdebase4-workspace-dbg"
Thanks :)

Are you running fglrx?

If I remember correctly, the file belongs to some X11 library, so it is probably not a bug in our code anyway. Which libX11/X server version are you using?

The reporter sent me an email:
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Sorry for the late replay, since this crash has occurred at work place, so, here is the back trace.

Application: System Settings (systemsettings), signal SIGABRT

Thread 1 (Thread 0xb61b16c0 (LWP 7301)):
[KCrash Handler]
#6  0xb80ea430 in __kernel_vsyscall ()
#7  0xb68ad880 in raise () from /lib/tls/i686/cmov/libc.so.6
#8  0xb68af248 in abort () from /lib/tls/i686/cmov/libc.so.6
#9  0xb68a672e in __assert_fail () from /lib/tls/i686/cmov/libc.so.6
#10 0xb664d66c in _XReply () from /usr/lib/libX11.so.6
#11 0xb663a217 in XQueryExtension () from /usr/lib/libX11.so.6
#12 0xb662e771 in XInitExtension () from /usr/lib/libX11.so.6
#13 0xb6608692 in XextAddDisplay () from /usr/lib/libXext.so.6
#14 0xb486bd9c in XF86DRICreateContextWithConfig () from /usr/lib/xorg/libGL.so.1
#15 0xb42cc735 in ?? () from /usr/lib/dri/fglrx_dri.so
#16 0xb484954f in ?? () from /usr/lib/xorg/libGL.so.1
#17 0xb4849948 in glXCreateContext () from /usr/lib/xorg/libGL.so.1
#18 0xb48bb090 in KWin::CompositingPrefs::initGLXContext (this=0x8b8eb78) at /build/buildd/kdebase-workspace-4.2.0/kwin/compositingprefs.cpp:198
#19 0xb48bcc2b in KWin::CompositingPrefs::detect (this=0x8b8eb78) at /build/buildd/kdebase-workspace-4.2.0/kwin/compositingprefs.cpp:159
#20 0xb48aeee8 in KWinCompositingConfig (this=0x8b8ea80, parent=0x8b80b00) at /build/buildd/kdebase-workspace-4.2.0/kwin/kcmkwin/kwincompositing/main.cpp:137
#21 0xb48b6731 in KPluginFactory::createInstance<KWin::KWinCompositingConfig, QWidget> (parentWidget=0x0, parent=0x8b80b00, args=@0xbfbe9700) at /usr/include/kpluginfactory.h:461
#22 0xb78d7f7f in KPluginFactory::create () from /usr/lib/libkdecore.so.5
#23 0xb8088ae6 in KService::createInstance<KCModule> () from /usr/lib/libkutils.so.4
#24 0xb8087952 in KCModuleLoader::loadModule () from /usr/lib/libkutils.so.4
#25 0xb808dd1d in ?? () from /usr/lib/libkutils.so.4
#26 0xb808ee43 in KCModuleProxy::realModule () from /usr/lib/libkutils.so.4
#27 0xb808efa8 in KCModuleProxy::buttons () from /usr/lib/libkutils.so.4
#28 0x0805459f in KCMultiWidget::slotAboutToShow (this=0x8b53548, page=0x8b80b00) at /build/buildd/kdebase-workspace-4.2.0/systemsettings/kcmultiwidget.cpp:264
#29 0x0805605a in KCMultiWidget::addModule (this=0x8b53548, moduleinfo=@0x8b02360) at /build/buildd/kdebase-workspace-4.2.0/systemsettings/kcmultiwidget.cpp:208
#30 0x0805b437 in MainWindow::selectionChanged (this=0x8a6d6e0, selected=@0x8a1f270) at /build/buildd/kdebase-workspace-4.2.0/systemsettings/mainwindow.cpp:365
#31 0x0805b63c in MainWindow::qt_metacall (this=0x8a6d6e0, _c=QMetaObject::InvokeMetaMethod, _id=0, _a=0xbfbe9cec)
  at /build/buildd/kdebase-workspace-4.2.0/obj-i486-linux-gnu/systemsettings/mainwindow.moc:70
#32 0xb75afa60 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#33 0xb75b07e2 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#34 0xb70ff603 in QAbstractItemView::activated () from /usr/lib/libQtGui.so.4
#35 0xb710c920 in QAbstractItemView::mouseReleaseEvent () from /usr/lib/libQtGui.so.4
#36 0xb71227ef in QListView::mouseReleaseEvent () from /usr/lib/libQtGui.so.4
#37 0xb7ad9d84 in KCategorizedView::mouseReleaseEvent () from /usr/lib/libkdeui.so.5
#38 0xb6c95962 in QWidget::event () from /usr/lib/libQtGui.so.4
#39 0xb6fccfd3 in QFrame::event () from /usr/lib/libQtGui.so.4
#40 0xb70637df in QAbstractScrollArea::viewportEvent () from /usr/lib/libQtGui.so.4
#41 0xb710eccf in QAbstractItemView::viewportEvent () from /usr/lib/libQtGui.so.4
#42 0xb7065d85 in ?? () from /usr/lib/libQtGui.so.4
#43 0xb759a04a in QCoreApplicationPrivate::sendThroughObjectEventFilters () from /usr/lib/libQtCore.so.4
#44 0xb6c3d8ca in QApplicationPrivate::notify_helper () from /usr/lib/libQtGui.so.4
#45 0xb6c460e1 in QApplication::notify () from /usr/lib/libQtGui.so.4
#46 0xb7aef06d in KApplication::notify () from /usr/lib/libkdeui.so.5
#47 0xb759ae61 in QCoreApplication::notifyInternal () from /usr/lib/libQtCore.so.4
#48 0xb6c4536e in QApplicationPrivate::sendMouseEvent () from /usr/lib/libQtGui.so.4
#49 0xb6caf656 in ?? () from /usr/lib/libQtGui.so.4
#50 0xb6cae9e5 in QApplication::x11ProcessEvent () from /usr/lib/libQtGui.so.4
#51 0xb6cd87aa in ?? () from /usr/lib/libQtGui.so.4
#52 0xb64e86f8 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#53 0xb64ebda3 in ?? () from /usr/lib/libglib-2.0.so.0
#54 0xb64ebf61 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#55 0xb75c5478 in QEventDispatcherGlib::processEvents () from /usr/lib/libQtCore.so.4
#56 0xb6cd7ea5 in ?? () from /usr/lib/libQtGui.so.4
#57 0xb759952a in QEventLoop::processEvents () from /usr/lib/libQtCore.so.4
#58 0xb75996ea in QEventLoop::exec () from /usr/lib/libQtCore.so.4
#59 0xb759bda5 in QCoreApplication::exec () from /usr/lib/libQtCore.so.4
#60 0xb6c3d767 in QApplication::exec () from /usr/lib/libQtGui.so.4
#61 0x080571ab in main (argc=1, argv=0xbfbeb1c4) at /build/buildd/kdebase-workspace-4.2.0/systemsettings/main.cpp:67

Same problem when I click on Desktop...

Running Gentoo Kde 4.2.1.

Graphics card: Ati Radeon
01:00.0 VGA compatible controller: ATI Technologies Inc Radeon RV250 [Mobility FireGL 9000] (rev 02)
Using Free Driver (not fglrx).

Here is the backtrace:

Application: System Settings (systemsettings), signal SIGSEGV

Thread 1 (Thread 0xb645d700 (LWP 7033)):
#0  0xb7f6a424 in __kernel_vsyscall ()
#1  0xb6a70430 in nanosleep () from /lib/libc.so.6
#2  0xb6a7027b in sleep () from /lib/libc.so.6
#3  0xb7a55db4 in ?? () from /usr/kde/4.2/lib/libkdeui.so.5
#4  0x00000001 in ?? ()
#5  0x00000000 in ?? ()

I think I've spotted the problem... it's when I do:

pol@r51 ~ $ kcmshell4 kwincompositing
Object::connect: No such slot KWin::KWinCompositingConfig::compositingModeChanged()
Object::connect:  (sender name:   'compositingType')
Object::connect:  (receiver name: 'KWinCompositingConfig')
KCrash: Application 'kcmshell4' crashing...
sock_file=/home/pol/.kde4.2/socket-r51/kdeinit4__0

Any idea ?

I've enabled xcomposite in the USE flag, recompiled kwin and now it works !!!

I've just installed recent KDE GNU/linux Mint in two computers, one of the an acer laptop with intel integrated for a friend, and other my desktop.

I've problems in both resizing, in the laptop it reinit each time I went in desktop, but it worked at restart. In my computer, (ati fglr, but too with OS drivers) I need to resize each login.

For LCD displays I suggest to put a option of - for example - 1024x768 aspect, yhat would give native resolution, but bigger icons, font size and so one. It would be easy to make scripts like that to resize all to bigger aspect, even with a percentage zoom - but inside the screen - to allow to read comfortable the firefox, menus and so.

@Miguel: I can't see how your comment is related to the crash reported in this bug.

The initial reporter's problem is most probably caused by some bug in the graphics driver. The »no such slot«-warning has been fixed in r959605.

Bulk change: move all KWin kcm bugs to product kwin