Application that crashed: kontact
Version of the application: 4.3.0
KDE Version: 4.3.00 (KDE 4.3.0)
Qt Version: 4.5.2
Operating System: Linux 2.6.28-15-generic x86_64
Distribution: Ubuntu 9.04

What I was doing when the application crashed:
On login, as each application is launched from saved session data, for Kontact there is an attempt to launch Kontact twice - i.e. a warning dialogue is presented saying that Kontact is already running on another screen.
If 'Start' is selected two windows appear, on closing a window Kontact will crash - I try to avoid doing this and have done only once to see result.
In preference 'Exit' is clicked on dialogue and Kontact opens a single window however shortly after a crash occurs.

KDE is set to load a manually saved session.  I have edited Ksmserverrc and removed all session info including ./session/ files then re-saved the session to try to resolve the issue with multiple Kontact sessions being launched.

Previously I have been using Kmail standalone and it is since I began to use Kontact that this bug has begun to manifest itself.

 -- Backtrace:
Application: Kontact (kontact), signal: Segmentation fault
[KCrash Handler]
#5  0x00007f3e1266344f in KMKernel::config () from /usr/lib/libkmailprivate.so.4
#6  0x00007f3e1266431e in KMKernel::slotRunBackgroundTasks () from /usr/lib/libkmailprivate.so.4
#7  0x00007f3e126757a5 in KMKernel::qt_metacall () from /usr/lib/libkmailprivate.so.4
#8  0x00007f3e24de8ea2 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#9  0x00007f3e24de3263 in QObject::event () from /usr/lib/libQtCore.so.4
#10 0x00007f3e25951f4d in QApplicationPrivate::notify_helper () from /usr/lib/libQtGui.so.4
#11 0x00007f3e2595a18a in QApplication::notify () from /usr/lib/libQtGui.so.4
#12 0x00007f3e26d5671b in KApplication::notify () from /usr/lib/libkdeui.so.5
#13 0x00007f3e24dd36ac in QCoreApplication::notifyInternal () from /usr/lib/libQtCore.so.4
#14 0x00007f3e24e00516 in ?? () from /usr/lib/libQtCore.so.4
#15 0x00007f3e24dfcb2d in ?? () from /usr/lib/libQtCore.so.4
#16 0x00007f3e1e52420a in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#17 0x00007f3e1e5278e0 in ?? () from /usr/lib/libglib-2.0.so.0
#18 0x00007f3e1e527a7c in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#19 0x00007f3e24dfca8f in QEventDispatcherGlib::processEvents () from /usr/lib/libQtCore.so.4
#20 0x00007f3e259eabdf in ?? () from /usr/lib/libQtGui.so.4
#21 0x00007f3e24dd1f42 in QEventLoop::processEvents () from /usr/lib/libQtCore.so.4
#22 0x00007f3e24dd2314 in QEventLoop::exec () from /usr/lib/libQtCore.so.4
#23 0x00007f3e24dd45e4 in QCoreApplication::exec () from /usr/lib/libQtCore.so.4
#24 0x0000000000404945 in _start ()

Reported using DrKonqi