Version:           4.0.0 (using KDE 4.0.0)
Installed from:    Debian testing/unstable Packages
OS:                Linux

I went into systemsettings->keyboard & mouse->keyb. shortcuts

I chose "switch to desktop 1". It dissapeared and after some clicks appeared again. I double click on it and a dialog asking for custom keys appeared. I used meta key (Windows) and strange chars appeared. I don't remember if then I save it or not, but I got a SIGABRT with this backtrace:
Using host libthread_db library "/lib/libthread_db.so.1".
[Thread debugging using libthread_db enabled]
[New Thread 0x2aed7611d970 (LWP 3398)]
[KCrash handler]
#4  0x00002aed6feef025 in raise () from /lib/libc.so.6
#5  0x00002aed6fef0a80 in abort () from /lib/libc.so.6
#6  0x00002aed6dfc0685 in qt_message_output (msgType=QtFatalMsg, 
    buf=<value optimized out>) at global/qglobal.cpp:2160
#7  0x00002aed6dfc07a7 in qFatal (msg=<value optimized out>)
    at global/qglobal.cpp:2392
#8  0x00002aed6e94dfa9 in KExtendableItemDelegate::extenderDestructionHandler
    (this=0xa54190, destroyed=<value optimized out>)
    at /tmp/buildd/kde4libs-4.0.0/kdeui/itemviews/kextendableitemdelegate.cpp:106
#9  0x00002aed6e94e03e in KExtendableItemDelegate::qt_metacall (
    this=0xa54190, _c=QMetaObject::InvokeMetaMethod, _id=-1, 
    _a=0x7fff3cd50e80)
    at /tmp/buildd/kde4libs-4.0.0/obj-x86_64-linux-gnu/kdeui/kextendableitemdelegate.moc:73
#10 0x00002aed6e903f45 in KShortcutsEditorDelegate::qt_metacall (this=0xd46, 
    _c=3398, _id=6, _a=0xffffffffffffffff)
    at /tmp/buildd/kde4libs-4.0.0/obj-x86_64-linux-gnu/kdeui/kshortcutsdialog_p.moc:72
#11 0x00002aed6e07f271 in QMetaObject::activate (sender=0xa6fcf0, 
    from_signal_index=0, to_signal_index=1, argv=0xffffffffffffffff)
    at kernel/qobject.cpp:3087
#12 0x00002aed6e07f5c4 in QObject::destroyed (this=0xd46, _t1=0xa6fcf0)
    at .moc/debug-shared/moc_qobject.cpp:114
#13 0x00002aed6e07fb07 in ~QObject (this=0xa6fcf0) at kernel/qobject.cpp:802
#14 0x00002aed6f136c3d in ~QWidget (this=0xa6fcf0) at kernel/qwidget.cpp:1210
#15 0x00002aed6e9064af in ~ShortcutEditWidget (this=0xa6fcf0)
    at /tmp/buildd/kde4libs-4.0.0/kdeui/dialogs/kshortcutsdialog_p.h:62
#16 0x00002aed6e07ebe4 in QObjectPrivate::deleteChildren (this=0xa4d8f0)
    at kernel/qobject.cpp:1934
#17 0x00002aed6f141f85 in ~QWidget (this=0xa4d8b0) at kernel/qwidget.cpp:1197
#18 0x00002aed6e07ebe4 in QObjectPrivate::deleteChildren (this=0xa4bbe0)
    at kernel/qobject.cpp:1934
#19 0x00002aed6f136cbf in ~QWidget (this=0xa4b9d0) at kernel/qwidget.cpp:1197
#20 0x00002aed6f54cc41 in ~QTreeWidget (this=0xd46)
    at itemviews/qtreewidget.cpp:2463
#21 0x00002aed6e07ebe4 in QObjectPrivate::deleteChildren (this=0xa49880)
    at kernel/qobject.cpp:1934
#22 0x00002aed6f136cbf in ~QWidget (this=0xa497e0) at kernel/qwidget.cpp:1197
#23 0x00002aed6e90130b in ~KShortcutsEditor (this=0xa497e0)
    at /tmp/buildd/kde4libs-4.0.0/kdeui/dialogs/kshortcutsdialog.cpp:454
#24 0x00002aed6e07ebe4 in QObjectPrivate::deleteChildren (this=0xa47390)
    at kernel/qobject.cpp:1934
#25 0x00002aed6f136cbf in ~QWidget (this=0xa46d60) at kernel/qwidget.cpp:1197
#26 0x00002aed6e9e8b19 in ~KCModule (this=0xa46d60)
    at /tmp/buildd/kde4libs-4.0.0/kdeui/widgets/kcmodule.cpp:130
#27 0x00002aed7b826893 in ~GlobalShortcutsModule (this=0xa46d60)
    at /build/buildd/kdebase-workspace-4.0.0/kcontrol/keys/globalshortcuts.cpp:66
#28 0x00002aed6ed2aca4 in KCModuleProxy::deleteClient (
    this=<value optimized out>)
    at /tmp/buildd/kde4libs-4.0.0/kutils/kcmoduleproxy.cpp:216
#29 0x00002aed6ed2b4b6 in ~KCModuleProxy (this=0xd46)
    at /tmp/buildd/kde4libs-4.0.0/kutils/kcmoduleproxy.cpp:207
#30 0x00002aed6e07ebe4 in QObjectPrivate::deleteChildren (this=0xa44f90)
    at kernel/qobject.cpp:1934
#31 0x00002aed6f141f85 in ~QWidget (this=0xa44f50) at kernel/qwidget.cpp:1197
#32 0x00002aed6e07ebe4 in QObjectPrivate::deleteChildren (this=0xa42990)
    at kernel/qobject.cpp:1934
#33 0x00002aed6f136cbf in ~QWidget (this=0xa42700) at kernel/qwidget.cpp:1197
#34 0x00002aed6f478281 in ~QScrollArea (this=0xd46)
    at widgets/qscrollarea.cpp:165
#35 0x00002aed6e07ebe4 in QObjectPrivate::deleteChildren (this=0x9f7cc0)
    at kernel/qobject.cpp:1934
#36 0x00002aed6f136cbf in ~QWidget (this=0x810320) at kernel/qwidget.cpp:1197
#37 0x00002aed6e9895ce in ~KPageStackedWidget (this=0xd46)
    at /tmp/buildd/kde4libs-4.0.0/kdeui/paged/kpageview_p.h:38
#38 0x00002aed6e07ebe4 in QObjectPrivate::deleteChildren (this=0x971170)
    at kernel/qobject.cpp:1934
#39 0x00002aed6f136cbf in ~QWidget (this=0x970330) at kernel/qwidget.cpp:1197
#40 0x00002aed6e98c5c1 in ~KPageWidget (this=0xd46)
    at /tmp/buildd/kde4libs-4.0.0/kdeui/paged/kpagewidget.cpp:78
#41 0x00002aed6e07ebe4 in QObjectPrivate::deleteChildren (this=0x969310)
    at kernel/qobject.cpp:1934
#42 0x00002aed6f136cbf in ~QWidget (this=0x9f9ac0) at kernel/qwidget.cpp:1197
#43 0x0000000000415658 in ~KCMultiWidget (this=0x9f9ac0)
    at /build/buildd/kdebase-workspace-4.0.0/systemsettings/kcmultiwidget.cpp:119
#44 0x00002aed6e07ebe4 in QObjectPrivate::deleteChildren (this=0x83a310)
    at kernel/qobject.cpp:1934
#45 0x00002aed6f136cbf in ~QWidget (this=0x838180) at kernel/qwidget.cpp:1197
#46 0x00002aed6f4540e1 in ~QStackedWidget (this=0xd46)
    at widgets/qstackedwidget.cpp:151
#47 0x00002aed6e07ebe4 in QObjectPrivate::deleteChildren (this=0x76a150)
    at kernel/qobject.cpp:1934
#48 0x00002aed6f136cbf in ~QWidget (this=0x769fb0) at kernel/qwidget.cpp:1197
#49 0x00002aed6ea0d297 in ~KMainWindow (this=0x769fb0)
    at /tmp/buildd/kde4libs-4.0.0/kdeui/widgets/kmainwindow.cpp:370
#50 0x0000000000418374 in ~MainWindow (this=0x769fb0)
    at /build/buildd/kdebase-workspace-4.0.0/systemsettings/mainwindow.cpp:81
#51 0x00002aed6e07e62a in QObject::event (this=0xd46, e=0xffffffffffffffff)
    at kernel/qobject.cpp:1114
#52 0x00002aed6f13e61f in QWidget::event (this=0x769fb0, event=0xa701b0)
    at kernel/qwidget.cpp:6510
#53 0x00002aed6f416801 in QMainWindow::event (this=0x769fb0, event=0xa701b0)
    at widgets/qmainwindow.cpp:1194
#54 0x00002aed6ea09dfb in KMainWindow::event (this=0x769fb0, ev=0xa701b0)
    at /tmp/buildd/kde4libs-4.0.0/kdeui/widgets/kmainwindow.cpp:934
#55 0x00002aed6ea3b3b6 in KXmlGuiWindow::event (this=0xd46, ev=0xd46)
    at /tmp/buildd/kde4libs-4.0.0/kdeui/xmlgui/kxmlguiwindow.cpp:123
#56 0x00002aed6f0fc32b in QApplicationPrivate::notify_helper (this=0x64ef20, 
    receiver=0x769fb0, e=0xa701b0) at kernel/qapplication.cpp:3556
#57 0x00002aed6f0ffcb3 in QApplication::notify (this=0x7fff3cd522b0, 
    receiver=0x769fb0, e=0xa701b0) at kernel/qapplication.cpp:3497
#58 0x00002aed6e95caeb in KApplication::notify (this=0x7fff3cd522b0, 
    receiver=0x769fb0, event=0xa701b0)
    at /tmp/buildd/kde4libs-4.0.0/kdeui/kernel/kapplication.cpp:314
#59 0x00002aed6e06d420 in QCoreApplication::notifyInternal (
    this=0x7fff3cd522b0, receiver=0x769fb0, event=0xa701b0)
    at kernel/qcoreapplication.cpp:530
#60 0x00002aed6e06e7fa in QCoreApplicationPrivate::sendPostedEvents (
    receiver=0x0, event_type=0, data=0x635410)
    at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:200
#61 0x00002aed6e08e11c in postEventSourceDispatch (s=<value optimized out>)
    at kernel/qeventdispatcher_glib.cpp:207
#62 0x00002aed70aa8194 in g_main_context_dispatch ()
   from /usr/lib/libglib-2.0.so.0
#63 0x00002aed70aab495 in ?? () from /usr/lib/libglib-2.0.so.0
#64 0x00002aed70aab97b in g_main_context_iteration ()
   from /usr/lib/libglib-2.0.so.0
#65 0x00002aed6e08e451 in QEventDispatcherGlib::processEvents (this=0x64da20, 
    flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:338
#66 0x00002aed6f171c0f in QGuiEventDispatcherGlib::processEvents (this=0xd46, 
    flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:191
#67 0x00002aed6e06c908 in QEventLoop::processEvents (
    this=<value optimized out>, flags=<value optimized out>)
    at kernel/qeventloop.cpp:140
#68 0x00002aed6e06ca26 in QEventLoop::exec (this=0x7fff3cd52220, 
    flags=@0x7fff3cd52230) at kernel/qeventloop.cpp:182
#69 0x00002aed6e06eb81 in QCoreApplication::exec ()
    at kernel/qcoreapplication.cpp:759
#70 0x0000000000417f07 in main (argc=5, argv=0x7fff3cd525f8)
    at /build/buildd/kdebase-workspace-4.0.0/systemsettings/main.cpp:64
#71 0x00002aed6fedb1c4 in __libc_start_main () from /lib/libc.so.6
#72 0x0000000000412689 in _start ()
#0  0x00002aed6ff5a465 in waitpid () from /lib/libc.so.6

Unfortunately I didn't get to reproduce this problem, but trying to I got a funny SIGSEGV I'm about to report now :)

Hope this is helpful.