Here's the backtrace:

Application: KDE Control Module (kcmshell4), signal SIGABRT
[Thread debugging using libthread_db enabled]
[New Thread 0xb7dd1700 (LWP 17078)]
[KCrash handler]
#6  0xb7f1b424 in __kernel_vsyscall ()
#7  0x41049640 in raise () from /lib/i686/cmov/libc.so.6
#8  0x4104b018 in abort () from /lib/i686/cmov/libc.so.6
#9  0x41725cfd in qt_message_output (msgType=<value optimized out>, 
    buf=<value optimized out>) at global/qglobal.cpp:2061
#10 0x41725dc6 in qFatal (msg=<value optimized out>) at global/qglobal.cpp:2263
#11 0x41725e55 in qt_assert (assertion=) at global/qglobal.cpp:1831
#12 0x42deeb12 in KNFSShare::isDirectoryShared (this=<value optimized out>, 
    path=<value optimized out>) at /usr/include/qt4/QtCore/qstring.h:652
#13 0xb65ece14 in PropertiesPage::load (this=0x8e987c0)
    at /tmp/buildd/kdenetwork-4.1.0/filesharing/advanced/propsdlgplugin/propertiespage.cpp:125
#14 0xb65ed20c in PropertiesPage (this=0x8e987c0, parent=0x8b9e130, 
    items=@0xbf917918, enterUrl=true)
    at /tmp/buildd/kdenetwork-4.1.0/filesharing/advanced/propsdlgplugin/propertiespage.cpp:94
#15 0xb65a1f0a in PropertiesPageDlg (this=0x8b97e58, parent=0x8bb1140, files=
          {<QList<KFileItem>> = {{p = {static shared_null = {ref = {_q_value = 2851}, alloc = 0, begin = 0, end = 0, sharable = 1, array = {0x0}}, d = 0xbf917918}, d = 0xbf917918}}, <No data fields>})
    at /tmp/buildd/kdenetwork-4.1.0/filesharing/simple/fileshare.cpp:371
#16 0xb65a1fa9 in KFileShareConfig::showShareDialog (this=0x8bb1140, 
    files=@0xbf91794c)
    at /tmp/buildd/kdenetwork-4.1.0/filesharing/simple/fileshare.cpp:391
#17 0xb65a22b1 in KFileShareConfig::addShareBtnClicked (this=0x8bb1140)
    at /tmp/buildd/kdenetwork-4.1.0/filesharing/simple/fileshare.cpp:355
#18 0xb65a1d33 in KFileShareConfig::qt_metacall (this=0x8bb1140, 
    _c=QMetaObject::InvokeMetaMethod, _id=3, _a=0xbf917a6c)
    at /tmp/buildd/kdenetwork-4.1.0/obj-i486-linux-gnu/filesharing/simple/fileshare.moc:76
#19 0x41831ed0 in QMetaObject::activate (sender=<value optimized out>, 
    from_signal_index=<value optimized out>, 
    to_signal_index=<value optimized out>, argv=<value optimized out>)
    at kernel/qobject.cpp:3016
#20 0x418322d0 in QMetaObject::activate (sender=<value optimized out>, 
    m=<value optimized out>, from_local_signal_index=<value optimized out>, 
    to_local_signal_index=<value optimized out>, argv=)
    at kernel/qobject.cpp:3106
#21 0x42506061 in QAbstractButton::clicked (this=)
    at .moc/release-shared/moc_qabstractbutton.cpp:185
#22 0x4225a089 in QAbstractButtonPrivate::emitClicked (
    this=<value optimized out>) at widgets/qabstractbutton.cpp:544
#23 0x4225bc84 in QAbstractButtonPrivate::click (this=<value optimized out>)
    at widgets/qabstractbutton.cpp:537
#24 0x4225bf06 in QAbstractButton::mouseReleaseEvent (
    this=<value optimized out>, e=<value optimized out>)
    at widgets/qabstractbutton.cpp:1116
#25 0x41f75762 in QWidget::event (this=<value optimized out>, 
    event=<value optimized out>) at kernel/qwidget.cpp:7021
#26 0x42259f2e in QAbstractButton::event (this=<value optimized out>, 
    e=<value optimized out>) at widgets/qabstractbutton.cpp:1078
#27 0x423001d0 in QPushButton::event (this=<value optimized out>, 
    e=<value optimized out>) at widgets/qpushbutton.cpp:658
#28 0x41f1db8c in QApplicationPrivate::notify_helper (
    this=<value optimized out>, receiver=<value optimized out>, 
    e=<value optimized out>) at kernel/qapplication.cpp:3800
#29 0x41f26381 in QApplication::notify (this=<value optimized out>, 
    receiver=<value optimized out>, e=<value optimized out>)
    at kernel/qapplication.cpp:3527
#30 0x4290e5dd in KApplication::notify (this=<value optimized out>, 
    receiver=<value optimized out>, event=<value optimized out>)
    at /tmp/buildd/kde4libs-4.1.0/kdeui/kernel/kapplication.cpp:311
#31 0x4181d3af in QCoreApplication::notifyInternal (
    this=<value optimized out>, receiver=<value optimized out>, 
    event=<value optimized out>) at kernel/qcoreapplication.cpp:591
#32 0x41f2563e in QApplicationPrivate::sendMouseEvent (
    receiver=<value optimized out>, event=<value optimized out>, 
    alienWidget=<value optimized out>, nativeWidget=<value optimized out>, 
    buttonDown=<value optimized out>, lastMouseReceiver=<value optimized out>)
    at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:218
#33 0x41f8ed4d in QETWidget::translateMouseEvent (this=<value optimized out>, 
    event=<value optimized out>) at kernel/qapplication_x11.cpp:4048
#34 0x41f8da11 in QApplication::x11ProcessEvent (this=<value optimized out>, 
    event=<value optimized out>) at kernel/qapplication_x11.cpp:3166
#35 0x41fb7e98 in QEventDispatcherX11::processEvents (
    this=<value optimized out>, flags=<value optimized out>)
    at kernel/qeventdispatcher_x11.cpp:134
#36 0x4181ba7a in QEventLoop::processEvents (this=<value optimized out>, 
    flags=<value optimized out>) at kernel/qeventloop.cpp:149
#37 0x4181bc3a in QEventLoop::exec (this=<value optimized out>, 
    flags=<value optimized out>) at kernel/qeventloop.cpp:200
#38 0x42385197 in QDialog::exec (this=<value optimized out>)
    at dialogs/qdialog.cpp:453
#39 0x41daf446 in kdemain (_argc=<value optimized out>, 
    _argv=<value optimized out>)
    at /build/buildd/kdebase-runtime-4.1.0/kcmshell/main.cpp:275
#40 0x08048592 in main (argc=)
    at /build/buildd/kdebase-runtime-4.1.0/obj-i486-linux-gnu/kcmshell/kcmshell4_dummy.cpp:3
#0  0xb7f1b424 in __kernel_vsyscall ()

*** This bug has been marked as a duplicate of bug 160123 ***

@FiNeX: the backtrace in this bug is more similar to the one in bug 174126 than the one in bug 160123 (actually dupe of that bug)