Application that crashed: kmail
Version of the application: 1.12.0
KDE Version: 4.3.00 (KDE 4.3.0)
Qt Version: 4.5.2
Operating System: Linux 2.6.30-1-686 i686

What I was doing when the application crashed:
Just leaving the application (by clicking on the x on the right top), then KMail crashes.

 -- Backtrace:
Application: KMail (kmail), signal: Aborted
[Current thread is 1 (Thread 0xb3e06700 (LWP 5108))]

Thread 2 (Thread 0xafa58b90 (LWP 5151)):
#0  0xb7f66424 in __kernel_vsyscall ()
#1  0xb636bbb3 in __lll_lock_wait_private () at ../nptl/sysdeps/unix/sysv/linux/i386/i686/../i486/lowlevellock.S:89
#2  0xb62ef26d in _L_lock_4597 () from /lib/i686/cmov/libc.so.6
#3  0xb62eb88a in *__GI___libc_free (mem=0x8c072a0) at malloc.c:3623
#4  0xb4734796 in IA__g_free (mem=0x8c072a0) at /build/buildd-glib2.0_2.20.4-1-i386-6KfM1O/glib2.0-2.20.4/glib/gmem.c:190
#5  0xb472bd67 in g_source_unref_internal (source=0x8c072a0, context=0x8c0fda8, have_lock=0) at /build/buildd-glib2.0_2.20.4-1-i386-6KfM1O/glib2.0-2.20.4/glib/gmain.c:1203
#6  0xb70247a0 in ~QEventDispatcherGlib (this=0x8aebcb0, __in_chrg=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:289
#7  0xb6f075d8 in QThreadPrivate::finish (arg=0x81f2b50) at thread/qthread_unix.cpp:212
#8  0xb6f0752a in ~__pthread_cleanup_class (arg=0x81f2b50) at /usr/include/pthread.h:533
#9  QThreadPrivate::start (arg=0x81f2b50) at thread/qthread_unix.cpp:190
#10 0xb54b54b5 in start_thread (arg=0xafa58b90) at pthread_create.c:300
#11 0xb635ca5e in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:130

Thread 1 (Thread 0xb3e06700 (LWP 5108)):
[KCrash Handler]
#6  0xb7f66424 in __kernel_vsyscall ()
#7  0xb62a63d0 in *__GI_raise (sig=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:64
#8  0xb62a9a85 in *__GI_abort () at abort.c:88
#9  0xb62df2ed in __libc_message (do_abort=2, fmt=0xb63bc328 "*** glibc detected *** %s: %s: 0x%s ***\n") at ../sysdeps/unix/sysv/linux/libc_fatal.c:173
#10 0xb62e98f4 in malloc_printerr (action=2, str=0xb63b9204 "free(): invalid pointer", ptr=0x8ba1c10) at malloc.c:5994
#11 0xb62eb896 in *__GI___libc_free (mem=0x8ba1c10) at malloc.c:3625
#12 0xb64bc4b1 in operator delete(void*) () from /usr/lib/libstdc++.so.6
#13 0xb66342b5 in ~QAction (this=0x8ba1c10, __in_chrg=<value optimized out>) at kernel/qaction.cpp:622
#14 0xb700781f in QObjectPrivate::deleteChildren (this=0x88c1f28) at kernel/qobject.cpp:1846
#15 0xb6689a1b in ~QWidget (this=0x8af12c8, __in_chrg=<value optimized out>) at kernel/qwidget.cpp:1367
#16 0xb6a7948d in ~QMenu (this=0x8af12c8, __in_chrg=<value optimized out>) at widgets/qmenu.cpp:1375
#17 0xb7e7c97f in ~KMenu (this=0x8af12c8, __in_chrg=<value optimized out>) at ../../kdeui/widgets/kmenu.cpp:175
#18 0xb700781f in QObjectPrivate::deleteChildren (this=0x8314270) at kernel/qobject.cpp:1846
#19 0xb6689a1b in ~QWidget (this=0x81e89e0, __in_chrg=<value optimized out>) at kernel/qwidget.cpp:1367
#20 0xb6a51841 in ~QMainWindow (this=0x81e89e0, __in_chrg=<value optimized out>) at widgets/qmainwindow.cpp:331
#21 0xb7e7a594 in ~KMainWindow (this=0x81e89e0, __in_chrg=<value optimized out>) at ../../kdeui/widgets/kmainwindow.cpp:467
#22 0xb7ebcd27 in ~KXmlGuiWindow (this=0x81e89e0, __vtt_parm=0xb79727b4, __in_chrg=<value optimized out>) at ../../kdeui/xmlgui/kxmlguiwindow.cpp:127
#23 0xb72b043e in ~KMMainWin (this=0x81e89e0, __in_chrg=<value optimized out>, __vtt_parm=<value optimized out>) at ../../kmail/kmmainwin.cpp:106
#24 0xb7007505 in qDeleteInEventHandler (o=0x6) at kernel/qobject.cpp:3814
#25 0xb7008ddb in QObject::event (this=0x81e89e0, e=0x8bb04c8) at kernel/qobject.cpp:1093
#26 0xb668e040 in QWidget::event (this=0x81e89e0, event=0x8bb04c8) at kernel/qwidget.cpp:7946
#27 0xb6a523d7 in QMainWindow::event (this=0x81e89e0, event=0x8bb04c8) at widgets/qmainwindow.cpp:1399
#28 0xb7e785f7 in KMainWindow::event (this=0x81e89e0, ev=0x8bb04c8) at ../../kdeui/widgets/kmainwindow.cpp:1094
#29 0xb7ebd5bc in KXmlGuiWindow::event (this=0x81e89e0, ev=0x8bb04c8) at ../../kdeui/xmlgui/kxmlguiwindow.cpp:131
#30 0xb66387d4 in QApplicationPrivate::notify_helper (this=0x81f0a28, receiver=0x81e89e0, e=0x8bb04c8) at kernel/qapplication.cpp:4056
#31 0xb6640a12 in QApplication::notify (this=0xbfb7bba8, receiver=0x81e89e0, e=0x8bb04c8) at kernel/qapplication.cpp:4021
#32 0xb7d9600d in KApplication::notify (this=0xbfb7bba8, receiver=0x81e89e0, event=0x8bb04c8) at ../../kdeui/kernel/kapplication.cpp:302
#33 0xb6ff896b in QCoreApplication::notifyInternal (this=0xbfb7bba8, receiver=0x81e89e0, event=0x8bb04c8) at kernel/qcoreapplication.cpp:610
#34 0xb6ff95ae in QCoreApplication::sendEvent (receiver=0x0, event_type=0, data=0x81c9e60) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:213
#35 QCoreApplicationPrivate::sendPostedEvents (receiver=0x0, event_type=0, data=0x81c9e60) at kernel/qcoreapplication.cpp:1247
#36 0xb6ff978d in QCoreApplication::sendPostedEvents (receiver=0x0, event_type=0) at kernel/qcoreapplication.cpp:1140
#37 0xb7023baf in QCoreApplication::sendPostedEvents (s=0x81f2ad0) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:218
#38 postEventSourceDispatch (s=0x81f2ad0) at kernel/qeventdispatcher_glib.cpp:210
#39 0xb472c368 in g_main_dispatch (context=0x81f2a50) at /build/buildd-glib2.0_2.20.4-1-i386-6KfM1O/glib2.0-2.20.4/glib/gmain.c:1824
#40 IA__g_main_context_dispatch (context=0x81f2a50) at /build/buildd-glib2.0_2.20.4-1-i386-6KfM1O/glib2.0-2.20.4/glib/gmain.c:2377
#41 0xb472f8c3 in g_main_context_iterate (context=0x81f2a50, block=1, dispatch=1, self=0x81efa00) at /build/buildd-glib2.0_2.20.4-1-i386-6KfM1O/glib2.0-2.20.4/glib/gmain.c:2455
#42 0xb472fa48 in IA__g_main_context_iteration (context=0x81f2a50, may_block=1) at /build/buildd-glib2.0_2.20.4-1-i386-6KfM1O/glib2.0-2.20.4/glib/gmain.c:2518
#43 0xb70237f8 in QEventDispatcherGlib::processEvents (this=0x81c9bb0, flags=...) at kernel/qeventdispatcher_glib.cpp:327
#44 0xb66d7f85 in QGuiEventDispatcherGlib::processEvents (this=0x81c9bb0, flags=...) at kernel/qguieventdispatcher_glib.cpp:202
#45 0xb6ff6fba in QEventLoop::processEvents (this=0xbfb7bab0, flags=...) at kernel/qeventloop.cpp:149
#46 0xb6ff7402 in QEventLoop::exec (this=0xbfb7bab0, flags=...) at kernel/qeventloop.cpp:201
#47 0xb6ff9859 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#48 0xb6638657 in QApplication::exec () at kernel/qapplication.cpp:3525
#49 0x0804a6d0 in main (argc=) at ../../kmail/main.cpp:146

Reported using DrKonqi