Version:           1.11.0 (using 4.2.00 (KDE 4.2.0), Gentoo)
Compiler:          x86_64-pc-linux-gnu-gcc
OS:                Linux (x86_64) release 2.6.28-gentoo

Today, when I logged into my KDE-4.2.0 session I was greeted with the report that kontact had crashed. (See backtrace below)
While I dont really know why this crash happened, it might be of interest that before I logged out, I most likely had a kontact instance running, so I assume kontact crashed when trying to reload this old instance

Anyway, the backtrace was:

Application: Kontact (kontact), signal SIGABRT
0x00007f803a6fac70 in __nanosleep_nocancel () from /lib/libc.so.6
Current language:  auto; currently c

Thread 1 (Thread 0x7f8041075700 (LWP 30070)):
[KCrash Handler]
#5  0x00007f803a68d235 in *__GI_raise (sig=<value optimized out>) at ../nptl/sysdeps/unix/sysv/linux/raise.c:64
#6  0x00007f803a68e753 in *__GI_abort () at abort.c:88
#7  0x00007f803b3c98a5 in qt_message_output (msgType=QtFatalMsg, buf=<value optimized out>) at global/qglobal.cpp:2108
#8  0x00007f803b3c99e7 in qFatal (msg=<value optimized out>) at global/qglobal.cpp:2309
#9  0x00007f803d7d877c in KDBusServiceStarter (this=0xe46720) at /var/tmp/portage/kde-base/kdelibs-4.2.0-r1/work/kdelibs-4.2.0/kio/kio/kdbusservicestarter.cpp:54
#10 0x00007f8040055fea in ServiceStarter (this=0x7576, pluginList=0x7576) at /var/tmp/portage/kde-base/kontact-4.2.0-r1/work/kontact-4.2.0/kontact/src/mainwindow.cpp:107
#11 0x00007f80400525e0 in MainWindow (this=0x69dfc0) at /var/tmp/portage/kde-base/kontact-4.2.0-r1/work/kontact-4.2.0/kontact/src/mainwindow.cpp:152
#12 0x00000000004041fc in KontactApp::newInstance (this=0x7fff490c4e60) at /var/tmp/portage/kde-base/kontact-4.2.0-r1/work/kontact-4.2.0/kontact/src/main.cpp:134
#13 0x00007f803d3251cc in KUniqueApplicationAdaptor::newInstance (this=0x6cc6d0, asn_id=<value optimized out>, args=@0xe86430)
    at /var/tmp/portage/kde-base/kdelibs-4.2.0-r1/work/kdelibs-4.2.0/kdeui/kernel/kuniqueapplication_p.h:77
#14 0x00007f803d323bf2 in KUniqueApplicationAdaptor::qt_metacall (this=0x6cc6d0, _c=QMetaObject::InvokeMetaMethod, _id=0, _a=0x7fff490c2900)
    at /var/tmp/portage/kde-base/kdelibs-4.2.0-r1/work/kdelibs_build/kdeui/kuniqueapplication_p.moc:74
#15 0x00007f803b7da713 in QDBusConnectionPrivate::deliverCall (this=0x61fcc0, object=0x6cc6d0, msg=@0xf3fa70, metaTypes=@0x7fff490c2be8, slotIdx=4) at qdbusintegrator.cpp:855
#16 0x00007f803b7dba30 in QDBusConnectionPrivate::activateCall (this=0x61fcc0, object=0x6cc6d0, flags=337, msg=@0xf3fa70) at qdbusintegrator.cpp:760
#17 0x00007f803b7dc131 in QDBusConnectionPrivate::activateObject (this=0x61fcc0, node=@0xf3fa48, msg=@0xf3fa70, pathStartPos=<value optimized out>) at qdbusintegrator.cpp:1289
#18 0x00007f803b7dc448 in QDBusActivateObjectEvent::placeMetaCall (this=0xf3fa00) at qdbusintegrator.cpp:1406
#19 0x00007f803b4d6ddd in QObject::event (this=0x7fff490c4e60, e=0xf3fa00) at kernel/qobject.cpp:1152
#20 0x00007f803bfd2e99 in QApplication::event (this=0x7fff490c4e60, e=0xf3fa00) at kernel/qapplication.cpp:2193
#21 0x00007f803bfcd68d in QApplicationPrivate::notify_helper (this=0x634790, receiver=0x7fff490c4e60, e=0xf3fa00) at kernel/qapplication.cpp:3809
#22 0x00007f803bfd466e in QApplication::notify (this=0x7fff490c4e60, receiver=0x7fff490c4e60, e=0xf3fa00) at kernel/qapplication.cpp:3774
#23 0x00007f803d3212a8 in KApplication::notify (this=0x7fff490c4e60, receiver=0x7fff490c4e60, event=0xf3fa00)
    at /var/tmp/portage/kde-base/kdelibs-4.2.0-r1/work/kdelibs-4.2.0/kdeui/kernel/kapplication.cpp:307
#24 0x00007f803b4c69d0 in QCoreApplication::notifyInternal (this=0x7fff490c4e60, receiver=0x7fff490c4e60, event=0xf3fa00) at kernel/qcoreapplication.cpp:593
#25 0x00007f803b4c79bb in QCoreApplicationPrivate::sendPostedEvents (receiver=0x0, event_type=0, data=0x608c20) at kernel/qcoreapplication.h:215
#26 0x00007f803b4f2033 in postEventSourceDispatch (s=<value optimized out>) at kernel/qcoreapplication.h:220
#27 0x00007f80366192f7 in IA__g_main_context_dispatch (context=0x62d920) at gmain.c:2012
#28 0x00007f803661b1b7 in g_main_context_iterate (context=0x62d920, block=1, dispatch=1, self=<value optimized out>) at gmain.c:2645
#29 0x00007f803661b29d in IA__g_main_context_iteration (context=0x62d920, may_block=1) at gmain.c:2708
#30 0x00007f803b4f1d5f in QEventDispatcherGlib::processEvents (this=0x633610, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:325
#31 0x00007f803c06342f in QGuiEventDispatcherGlib::processEvents (this=0x7576, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:204
#32 0x00007f803b4c5582 in QEventLoop::processEvents (this=<value optimized out>, flags={i = 1225537376}) at kernel/qeventloop.cpp:149
#33 0x00007f803b4c570d in QEventLoop::exec (this=0x7fff490c37a0, flags={i = 1225537472}) at kernel/qeventloop.cpp:200
#34 0x00007f803c41da05 in QDialog::exec (this=0x7fff490c3810) at dialogs/qdialog.cpp:453
#35 0x00007f802d3eb789 in KMail::ImapAccountBase::makeConnection (this=0xbf2170) at /var/tmp/portage/kde-base/kmail-4.2.0-r1/work/kmail-4.2.0/kmail/imapaccountbase.cpp:320
#36 0x00007f802d4072da in KMFolderImap::listDirectory (this=0xaca8d0) at /var/tmp/portage/kde-base/kmail-4.2.0-r1/work/kmail-4.2.0/kmail/kmfolderimap.cpp:743
#37 0x00007f802d343d6e in KMail::FolderView::slotFolderExpanded (this=<value optimized out>, item=0xe2dc50) at /var/tmp/portage/kde-base/kmail-4.2.0-r1/work/kmail-4.2.0/kmail/folderview.cpp:2463
#38 0x00007f802d34a7da in KMail::FolderView::qt_metacall (this=0xdbadb0, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0x7fff490c3bf0)
    at /var/tmp/portage/kde-base/kmail-4.2.0-r1/work/kmail_build/kmail/folderview.moc:216
#39 0x00007f802d34e55e in KMail::MainFolderView::qt_metacall (this=0x7576, _c=30070, _id=6, _a=0xffffffffffffffff)
    at /var/tmp/portage/kde-base/kmail-4.2.0-r1/work/kmail_build/kmail/mainfolderview.moc:63
#40 0x00007f803b4dd2ac in QMetaObject::activate (sender=0xdbadb0, from_signal_index=<value optimized out>, to_signal_index=97, argv=0xffffffffffffffff) at kernel/qobject.cpp:3028
#41 0x00007f803c4ec732 in QTreeWidget::itemExpanded (this=0x7576, _t1=0xe2dc50) at .moc/debug-shared/moc_qtreewidget.cpp:234
#42 0x00007f803c4f901b in QTreeWidget::qt_metacall (this=0xdbadb0, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0x7fff490c3de0) at .moc/debug-shared/moc_qtreewidget.cpp:148
#43 0x00007f803fb63fec in KPIM::TreeWidget::qt_metacall (this=0x7576, _c=30070, _id=6, _a=0xffffffffffffffff)
    at /var/tmp/portage/kde-base/libkdepim-4.2.0/work/libkdepim_build/libkdepim/moc_treewidget.cpp:67
#44 0x00007f803fb640d9 in KPIM::FolderTreeWidget::qt_metacall (this=0x7576, _c=30070, _id=6, _a=0xffffffffffffffff)
    at /var/tmp/portage/kde-base/libkdepim-4.2.0/work/libkdepim_build/libkdepim/moc_foldertreewidget.cpp:63
#45 0x00007f802d34a5f2 in KMail::FolderView::qt_metacall (this=0x7576, _c=30070, _id=6, _a=0xffffffffffffffff) at /var/tmp/portage/kde-base/kmail-4.2.0-r1/work/kmail_build/kmail/folderview.moc:183
#46 0x00007f802d34e55e in KMail::MainFolderView::qt_metacall (this=0x7576, _c=30070, _id=6, _a=0xffffffffffffffff)
    at /var/tmp/portage/kde-base/kmail-4.2.0-r1/work/kmail_build/kmail/mainfolderview.moc:63
#47 0x00007f803b4dd2ac in QMetaObject::activate (sender=0xdbadb0, from_signal_index=<value optimized out>, to_signal_index=68, argv=0xffffffffffffffff) at kernel/qobject.cpp:3028
#48 0x00007f803c4ac2f2 in QTreeView::expanded (this=0x7576, _t1=<value optimized out>) at .moc/debug-shared/moc_qtreeview.cpp:204
#49 0x00007f803c4bcad2 in QTreeViewPrivate::expand (this=0xdbfc60, item=1, emitSignal=true) at itemviews/qtreeview.cpp:2811
#50 0x00007f803c4bdfaf in QTreeView::expand (this=0xdbadb0, index=@0x7fff490c3f90) at itemviews/qtreeview.cpp:761
#51 0x00007f803c4f929b in QTreeWidget::setItemExpanded (this=0xdbadb0, item=0xe2dc50, expand=6) at itemviews/qtreewidget.cpp:3074
#52 0x00007f802d349b88 in KMail::FolderView::restoreItemStates (this=0x7fff490c4050) at /var/tmp/portage/kde-base/kmail-4.2.0-r1/work/kmail-4.2.0/kmail/folderview.cpp:377
#53 0x00007f802d34a25f in KMail::FolderView::reload (this=0xdbadb0, openFoldersForUpdate=false) at /var/tmp/portage/kde-base/kmail-4.2.0-r1/work/kmail-4.2.0/kmail/folderview.cpp:667
#54 0x00007f802d4c2237 in KMMainWidget::readConfig (this=0xcb7fa0) at /var/tmp/portage/kde-base/kmail-4.2.0-r1/work/kmail-4.2.0/kmail/kmmainwidget.cpp:595
#55 0x00007f802d4c327c in KMMainWidget (this=0xcb7fa0, parent=0xbe0c90, aGUIClient=0x973f18, actionCollection=0x963340, config=0x627430)
    at /var/tmp/portage/kde-base/kmail-4.2.0-r1/work/kmail-4.2.0/kmail/kmmainwidget.cpp:233
#56 0x00007f802d9a47be in KMailPart (this=0x973ed0, parentWidget=<value optimized out>, parent=<value optimized out>)
    at /var/tmp/portage/kde-base/kmail-4.2.0-r1/work/kmail-4.2.0/kmail/kmail_part.cpp:111
#57 0x00007f802d9a56d4 in KPluginFactory::createPartInstance<KMailPart> (parentWidget=0x785ca0, parent=0x785ca0, args=@0x7fff490c46d0) at /usr/include/kpluginfactory.h:467
#58 0x00007f803bb943b1 in KPluginFactory::create (this=0x962730, iface=0x7f803db7fdf0 "KParts::ReadOnlyPart", parentWidget=0x785ca0, parent=0x785ca0, args=@0x7fff490c46d0, 
    keyword=<value optimized out>) at /var/tmp/portage/kde-base/kdelibs-4.2.0-r1/work/kdelibs-4.2.0/kdecore/util/kpluginfactory.cpp:191
#59 0x00007f803fe2b052 in KPluginFactory::create<KParts::ReadOnlyPart> (this=0x962730, parent=0x785ca0, args=@0x7fff490c46d0) at /usr/include/kpluginfactory.h:491
#60 0x00007f803fe2a345 in Kontact::Core::createPart (this=0x785ca0, libname=0x95a0d8 "kmailpart")
    at /var/tmp/portage/kde-base/kontactinterfaces-4.2.0/work/kontactinterfaces-4.2.0/kontactinterfaces/core.cpp:87
#61 0x00007f802ddd0a80 in KMailPlugin::createPart (this=0x7576) at /var/tmp/portage/kde-base/kmail-4.2.0-r1/work/kmail-4.2.0/kontact/plugins/kmail/kmail_plugin.cpp:170
#62 0x00007f803fe2b4a1 in Kontact::Plugin::part (this=0x7576) at /var/tmp/portage/kde-base/kontactinterfaces-4.2.0/work/kontactinterfaces-4.2.0/kontactinterfaces/plugin.cpp:187
#63 0x00007f804004e4f6 in Kontact::MainWindow::selectPlugin (this=0x785ca0, plugin=0x959ca0) at /var/tmp/portage/kde-base/kontact-4.2.0-r1/work/kontact-4.2.0/kontact/src/mainwindow.cpp:752
#64 0x00007f804004e1ad in Kontact::MainWindow::loadSettings (this=0x785ca0) at /var/tmp/portage/kde-base/kontact-4.2.0-r1/work/kontact-4.2.0/kontact/src/mainwindow.cpp:924
#65 0x00007f8040051fe6 in Kontact::MainWindow::initObject (this=0x785ca0) at /var/tmp/portage/kde-base/kontact-4.2.0-r1/work/kontact-4.2.0/kontact/src/mainwindow.cpp:226
#66 0x00007f8040052647 in MainWindow (this=0x785ca0) at /var/tmp/portage/kde-base/kontact-4.2.0-r1/work/kontact-4.2.0/kontact/src/mainwindow.cpp:162
#67 0x0000000000404062 in main (argc=3, argv=0x7fff490c5378) at /var/tmp/portage/kde-base/kontact-4.2.0-r1/work/kontact-4.2.0/kontact/src/main.cpp:210