Application: kontact (4.4.7)
KDE Platform Version: 4.5.2 (KDE 4.5.2)
Qt Version: 4.7.0
Operating System: Linux 2.6.35.6-48.fc14.i686 i686
Distribution: "Fedora release 14 (Laughlin)"

-- Information about the crash:
- What I was doing when the application crashed:
Finishing starting up my system.
- Unusual behavior I noticed:
I got a prompt that said: "Kontact already seems to be running on another display on this machine. Running Kontact more than once can cause the loss of mail. You should not start Kontact unless you are sure that it is not already running."
First time I exited the prompt without starting Kontact 'again', but after that I had no kmail icon in system tray nor the kontact program in System Monitor.
Second time around (and third and forth) I clicked on Start Kontact button on the specified prompt only to notice two instances of kontact running, with the crash occuring soon after.
- Custom settings of the application:
Kmail is set to always show the icon in the system tray, therefore running always in the background.

The crash can be reproduced every time.

-- Backtrace:
Application: Kontact (kontact), signal: Segmentation fault
[Current thread is 1 (Thread 0xb775f9b0 (LWP 2165))]

Thread 2 (Thread 0xb0c1ab70 (LWP 2399)):
#0  0x0033b416 in __kernel_vsyscall ()
#1  0x00b84d33 in pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/i386/i486/pthread_cond_timedwait.S:236
#2  0x031cc460 in wait (this=0x8c100fc, mutex=0x8c100f8, time=30000) at thread/qwaitcondition_unix.cpp:86
#3  QWaitCondition::wait (this=0x8c100fc, mutex=0x8c100f8, time=30000) at thread/qwaitcondition_unix.cpp:160
#4  0x031c1bd9 in QThreadPoolThread::run (this=0x8b8eff0) at concurrent/qthreadpool.cpp:140
#5  0x031cbdea in QThreadPrivate::start (arg=0x8b8eff0) at thread/qthread_unix.cpp:266
#6  0x00b7ff19 in start_thread (arg=0xb0c1ab70) at pthread_create.c:301
#7  0x00a8ea2e in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:133

Thread 1 (Thread 0xb775f9b0 (LWP 2165)):
[KCrash Handler]
#7  0x06fb430c in QString (this=0x928feb8) at /usr/include/QtCore/qstring.h:727
#8  Akregator::TreeNode::title (this=0x928feb8) at /usr/src/debug/kdepim-4.4.7/akregator/src/treenode.cpp:88
#9  0x070176a2 in Akregator::NotificationManager::doNotify (this=0x9262a08) at /usr/src/debug/kdepim-4.4.7/akregator/src/notificationmanager.cpp:99
#10 0x07017cab in Akregator::NotificationManager::qt_metacall (this=0x9262a08, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0xbfae982c) at /usr/src/debug/kdepim-4.4.7/i686-redhat-linux-gnu/akregator/src/notificationmanager.moc:79
#11 0x032c9e3b in QMetaObject::metacall (object=0x9262a08, cl=QMetaObject::InvokeMetaMethod, idx=6, argv=0xbfae982c) at kernel/qmetaobject.cpp:237
#12 0x032d9327 in QMetaObject::activate (sender=0x9289a00, m=0x33fe6c4, local_signal_index=0, argv=0x0) at kernel/qobject.cpp:3272
#13 0x032e0068 in QSingleShotTimer::timeout (this=0x9289a00) at .moc/release-shared/qtimer.moc:82
#14 0x032e011d in QSingleShotTimer::timerEvent (this=0x9289a00) at kernel/qtimer.cpp:308
#15 0x032d8c84 in QObject::event (this=0x9289a00, e=0xbfae9d50) at kernel/qobject.cpp:1175
#16 0x0382bd5c in QApplicationPrivate::notify_helper (this=0x83f50f8, receiver=0x9289a00, e=0xbfae9d50) at kernel/qapplication.cpp:4396
#17 0x038308f2 in QApplication::notify (this=0xbfaea094, receiver=0x9289a00, e=0xbfae9d50) at kernel/qapplication.cpp:3798
#18 0x0473fdab in KApplication::notify (this=0xbfaea094, receiver=0x9289a00, event=0xbfae9d50) at /usr/src/debug/kdelibs-4.5.2/kdeui/kernel/kapplication.cpp:310
#19 0x032c3633 in QCoreApplication::notifyInternal (this=0xbfaea094, receiver=0x9289a00, event=0xbfae9d50) at kernel/qcoreapplication.cpp:732
#20 0x032f3f7e in sendEvent (this=0x83f92cc) at kernel/qcoreapplication.h:215
#21 QTimerInfoList::activateTimers (this=0x83f92cc) at kernel/qeventdispatcher_unix.cpp:602
#22 0x032f0ba5 in timerSourceDispatch (source=0x83f9298) at kernel/qeventdispatcher_glib.cpp:184
#23 0x0050b192 in g_main_dispatch (context=0x83f8a90) at gmain.c:2149
#24 g_main_context_dispatch (context=0x83f8a90) at gmain.c:2702
#25 0x0050b978 in g_main_context_iterate (context=0x83f8a90, block=1, dispatch=1, self=<value optimized out>) at gmain.c:2780
#26 0x0050bc35 in g_main_context_iteration (context=0x83f8a90, may_block=1) at gmain.c:2843
#27 0x032f130d in QEventDispatcherGlib::processEvents (this=0x83cfb50, flags=...) at kernel/qeventdispatcher_glib.cpp:415
#28 0x038ddad6 in QGuiEventDispatcherGlib::processEvents (this=0x83cfb50, flags=...) at kernel/qguieventdispatcher_glib.cpp:204
#29 0x032c27ca in QEventLoop::processEvents (this=0xbfae9ff4, flags=...) at kernel/qeventloop.cpp:149
#30 0x032c2a7a in QEventLoop::exec (this=0xbfae9ff4, flags=...) at kernel/qeventloop.cpp:201
#31 0x032c75f7 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1009
#32 0x03829b98 in QApplication::exec () at kernel/qapplication.cpp:3672
#33 0x0804b73b in main (argc=1047683644, argv=0x77654e00) at /usr/src/debug/kdepim-4.4.7/kontact/src/main.cpp:224

Reported using DrKonqi