Application that crashed: kontact
Version of the application: 4.3.5
KDE Version: 4.3.5 (KDE 4.3.5)
Qt Version: 4.5.2
Operating System: Linux 2.6.31-20-generic x86_64
Distribution: Ubuntu 9.10

What I was doing when the application crashed:
1.  Start Kontact
2.  Switch to To-Do list.  There should already me 10-20 to-dos  and a bunch of completed ones
3.  The order they are in is somewhat random and completed to-dos are often above other uncompleted to-dos
4.  Search for a general named to-do or create one that can be a subject name for a series of sub-tos that are related.
5.  Try to move an existing sub-to-do that is uncomplete or completed to the subject to-do to organzie
6.  Kontact crashes every time.

 -- Backtrace:
Application: Kontact (kontact), signal: Segmentation fault
The current source language is "auto; currently c".
[KCrash Handler]
#5  0x00007fab98f66170 in QListData::size (this=0x27b01a0, parent=...) at /usr/include/qt4/QtCore/qlist.h:87
#6  QList<KOTodoModel::TodoTreeNode*>::count (this=0x27b01a0, parent=...) at /usr/include/qt4/QtCore/qlist.h:250
#7  KOTodoModel::TodoTreeNode::childrenCount (this=0x27b01a0, parent=...) at ../../korganizer/views/todoview/kotodomodel.cpp:161
#8  KOTodoModel::rowCount (this=0x27b01a0, parent=...) at ../../korganizer/views/todoview/kotodomodel.cpp:648
#9  0x00007fab98f65fdc in KOTodoModel::index (this=0x27b01a0, row=1, column=0, parent=...) at ../../korganizer/views/todoview/kotodomodel.cpp:609
#10 0x00007fabb9e0ee96 in void QAlgorithmsPrivate::qMerge<int*, int const, QSortFilterProxyModelLessThan>(int*, int*, int*, int const&, QSortFilterProxyModelLessThan) () from /usr/lib/libQtGui.so.4
#11 0x00007fabb9e0f07c in void QAlgorithmsPrivate::qStableSortHelper<int*, int, QSortFilterProxyModelLessThan>(int*, int*, int const&, QSortFilterProxyModelLessThan) () from /usr/lib/libQtGui.so.4
#12 0x00007fabb9e05ad1 in qStableSort<int*, QSortFilterProxyModelLessThan> (this=<value optimized out>, source_rows=..., source_parent=<value optimized out>)
    at ../../include/QtCore/../../src/corelib/tools/qalgorithms.h:229
#13 QSortFilterProxyModelPrivate::sort_source_rows (this=<value optimized out>, source_rows=..., source_parent=<value optimized out>) at itemviews/qsortfilterproxymodel.cpp:397
#14 0x00007fabb9e07251 in QSortFilterProxyModelPrivate::sort (this=0x279d2e0) at itemviews/qsortfilterproxymodel.cpp:362
#15 0x00007fabb9dc9085 in QTreeView::qt_metacall (this=0x27a9c50, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0x7fff895e3390) at .moc/release-shared/moc_qtreeview.cpp:153
#16 0x00007fab98f6eba0 in KOTodoViewView::qt_metacall (this=0x27b01a0, _c=2304651320, _id=41547009, _a=0x0) at ./kotodoviewview.moc:62
#17 0x00007fabb8f9dddc in QMetaObject::activate (sender=0x27ba570, from_signal_index=<value optimized out>, to_signal_index=<value optimized out>, argv=0x0) at kernel/qobject.cpp:3113
#18 0x00007fabb9d8b77f in QHeaderView::sortIndicatorChanged (this=0x27b01a0, _t1=0, _t2=Qt::AscendingOrder) at .moc/release-shared/moc_qheaderview.cpp:278
#19 0x00007fabb9d96c08 in QHeaderView::mouseReleaseEvent (this=0x27ba570, e=<value optimized out>) at itemviews/qheaderview.cpp:2286
#20 0x00007fabb98fb9c0 in QWidget::event (this=0x27ba570, event=0x7fff895e3f30) at kernel/qwidget.cpp:7549
#21 0x00007fabb9c572a6 in QFrame::event (this=0x27ba570, e=0x7fff895e3f30) at widgets/qframe.cpp:559
#22 0x00007fabb9d8a21b in QAbstractItemView::viewportEvent (this=0x27ba570, event=0x7fff895e3f30) at itemviews/qabstractitemview.cpp:1476
#23 0x00007fabb9d9371b in QHeaderView::viewportEvent (this=0x27ba570, e=0x7fff895e3f30) at itemviews/qheaderview.cpp:2400
#24 0x00007fabb8f87f47 in QCoreApplicationPrivate::sendThroughObjectEventFilters (this=<value optimized out>, receiver=0x27ba540, event=0x7fff895e3f30) at kernel/qcoreapplication.cpp:726
#25 0x00007fabb98acecc in QApplicationPrivate::notify_helper (this=0x15a9e90, receiver=0x27ba540, e=0x7fff895e3f30) at kernel/qapplication.cpp:4052
#26 0x00007fabb98b4011 in QApplication::notify (this=<value optimized out>, receiver=0x27ba540, e=0x7fff895e3f30) at kernel/qapplication.cpp:3758
#27 0x00007fabba4e3f46 in KApplication::notify (this=0x7fff895e5e50, receiver=0x27ba540, event=0x7fff895e3f30) at ../../kdeui/kernel/kapplication.cpp:302
#28 0x00007fabb8f88c2c in QCoreApplication::notifyInternal (this=0x7fff895e5e50, receiver=0x27ba540, event=0x7fff895e3f30) at kernel/qcoreapplication.cpp:610
#29 0x00007fabb98b38e0 in QCoreApplication::sendSpontaneousEvent (receiver=0x27ba540, event=0x7fff895e3f30, alienWidget=0x27ba540, nativeWidget=0x16cbe20, buttonDown=<value optimized out>, 
    lastMouseReceiver=<value optimized out>) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:216
#30 QApplicationPrivate::sendMouseEvent (receiver=0x27ba540, event=0x7fff895e3f30, alienWidget=0x27ba540, nativeWidget=0x16cbe20, buttonDown=<value optimized out>, 
    lastMouseReceiver=<value optimized out>) at kernel/qapplication.cpp:2924
#31 0x00007fabb9919a0e in QETWidget::translateMouseEvent (this=0x16cbe20, event=<value optimized out>) at kernel/qapplication_x11.cpp:4409
#32 0x00007fabb9918aa9 in QApplication::x11ProcessEvent (this=<value optimized out>, event=0x7fff895e5a60) at kernel/qapplication_x11.cpp:3550
#33 0x00007fabb9941d0c in x11EventSourceDispatch (s=<value optimized out>, callback=<value optimized out>, user_data=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:146
#34 0x00007fabb2800bce in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#35 0x00007fabb2804598 in ?? () from /lib/libglib-2.0.so.0
#36 0x00007fabb28046c0 in g_main_context_iteration () from /lib/libglib-2.0.so.0
#37 0x00007fabb8fb11a6 in QEventDispatcherGlib::processEvents (this=0x156acb0, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:327
#38 0x00007fabb99414be in QGuiEventDispatcherGlib::processEvents (this=0x27b01a0, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:202
#39 0x00007fabb8f87532 in QEventLoop::processEvents (this=<value optimized out>, flags=) at kernel/qeventloop.cpp:149
#40 0x00007fabb8f87904 in QEventLoop::exec (this=0x7fff895e5d90, flags=) at kernel/qeventloop.cpp:201
#41 0x00007fabb8f89ab9 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#42 0x0000000000403f47 in main (argc=<value optimized out>, argv=<value optimized out>) at ../../../kontact/src/main.cpp:218

Reported using DrKonqi