Application that crashed: kontact
Version of the application: 4.3.4
KDE Version: 4.3.4 (KDE 4.3.4)
Qt Version: 4.5.2
Operating System: Linux 2.6.31-16-generic x86_64
Distribution: Ubuntu 9.10

What I was doing when the application crashed:
Kontact/Kmail crashes everytime I try to compose an email (or reply to one); the crash occurs immediately after I click New Message (or Reply, Forward etc.); this is perfectly reproducable. I tried reinstalling kmail and rebooting - to no avail...

 -- Backtrace:
Application: Kontact (kontact), signal: Segmentation fault
[KCrash Handler]
#5  0x0000000000000110 in ?? ()
#6  0x00007fc77c648e5c in QObjectPrivate::deleteChildren (this=0x2bdf9e0) at kernel/qobject.cpp:1847
#7  0x00007fc77cfa94f3 in ~QWidget (this=0x2b31c50, __in_chrg=<value optimized out>) at kernel/qwidget.cpp:1367
#8  0x00007fc77c648e5c in QObjectPrivate::deleteChildren (this=0x2be0530) at kernel/qobject.cpp:1847
#9  0x00007fc77cfa9993 in ~QWidget (this=0x2b616c0, __in_chrg=<value optimized out>) at kernel/qwidget.cpp:1367
#10 0x00007fc77d368728 in ~QSplitter (this=0x2b616c0, __in_chrg=<value optimized out>) at widgets/qsplitter.cpp:1008
#11 0x00007fc77c648e5c in QObjectPrivate::deleteChildren (this=0x2bde0e0) at kernel/qobject.cpp:1847
#12 0x00007fc77cfa94f3 in ~QWidget (this=0x2b31c80, __in_chrg=<value optimized out>) at kernel/qwidget.cpp:1367
#13 0x00007fc77c648e5c in QObjectPrivate::deleteChildren (this=0x2b08a10) at kernel/qobject.cpp:1847
#14 0x00007fc77cfa9993 in ~QWidget (this=0x2b60fe0, __in_chrg=<value optimized out>) at kernel/qwidget.cpp:1367
#15 0x00007fc77dc67515 in ~KMainWindow (this=0x2b60fe0, __in_chrg=<value optimized out>) at ../../kdeui/widgets/kmainwindow.cpp:474
#16 0x00007fc766d1ed25 in ?? () from /usr/lib/libkmailprivate.so.4
#17 0x00007fc766ab5f4c in ?? () from /usr/lib/libkmailprivate.so.4
#18 0x00007fc766aaf643 in ?? () from /usr/lib/libkmailprivate.so.4
#19 0x00007fc766aafb44 in ?? () from /usr/lib/libkmailprivate.so.4
#20 0x00007fc766be3d7d in KMKernel::newMessage(QString const&, QString const&, QString const&, bool, bool, QString const&, QString const&) () from /usr/lib/libkmailprivate.so.4
#21 0x00007fc766e482ee in ?? () from /usr/lib/libkmailprivate.so.4
#22 0x00007fc77a76aad4 in QDBusConnectionPrivate::deliverCall (this=<value optimized out>, object=<value optimized out>, msg=<value optimized out>, metaTypes=..., slotIdx=<value optimized out>)
    at qdbusintegrator.cpp:891
#23 0x00007fc77a76bc69 in QDBusConnectionPrivate::activateCall (this=<value optimized out>, object=0x12340e0, flags=273, msg=...) at qdbusintegrator.cpp:796
#24 0x00007fc77a76c547 in QDBusConnectionPrivate::activateObject (this=<value optimized out>, node=..., msg=<value optimized out>, pathStartPos=<value optimized out>) at qdbusintegrator.cpp:1347
#25 0x00007fc77a76cf11 in QDBusConnectionPrivate::handleObjectCall (this=<value optimized out>, msg=<value optimized out>) at qdbusintegrator.cpp:1443
#26 0x00007fc77a76d305 in QDBusConnectionPrivate::handleMessage (this=<value optimized out>, amsg=...) at qdbusintegrator.cpp:535
#27 0x00007fc77a76d5dd in QDBusConnectionPrivate::sendWithReplyLocal (this=0xd20a50, message=...) at qdbusintegrator.cpp:1797
#28 0x00007fc77a76e3bb in QDBusConnectionPrivate::sendWithReplyAsync (this=0xd20a50, message=..., timeout=<value optimized out>) at qdbusintegrator.cpp:1832
#29 0x00007fc77a7575d0 in QDBusConnection::asyncCall (this=<value optimized out>, message=..., timeout=0) at qdbusconnection.cpp:542
#30 0x00007fc77a775efb in QDBusAbstractInterface::asyncCallWithArgumentList (this=<value optimized out>, method=..., args=<value optimized out>) at qdbusabstractinterface.cpp:430
#31 0x00007fc767f3e26e in ?? () from /usr/lib/kde4/kontact_kmailplugin.so
#32 0x00007fc767f3e3ed in ?? () from /usr/lib/kde4/kontact_kmailplugin.so
#33 0x00007fc767f3e440 in ?? () from /usr/lib/kde4/kontact_kmailplugin.so
#34 0x00007fc77c64fddc in QMetaObject::activate (sender=0xd9f620, from_signal_index=<value optimized out>, to_signal_index=<value optimized out>, argv=0x0) at kernel/qobject.cpp:3113
#35 0x00007fc77cf590a7 in QAction::triggered (this=0x2bd7360, _t1=false) at .moc/release-shared/moc_qaction.cpp:236
#36 0x00007fc77cf5a4ef in QAction::activate (this=0xd9f620, event=<value optimized out>) at kernel/qaction.cpp:1160
#37 0x00007fc77e50d153 in Kontact::MainWindow::qt_metacall(QMetaObject::Call, int, void**) () from /usr/lib/libkontactprivate.so.4
#38 0x00007fc77c64fddc in QMetaObject::activate (sender=0x10b6e10, from_signal_index=<value optimized out>, to_signal_index=<value optimized out>, argv=0x0) at kernel/qobject.cpp:3113
#39 0x00007fc77cf590a7 in QAction::triggered (this=0x2bd7360, _t1=false) at .moc/release-shared/moc_qaction.cpp:236
#40 0x00007fc77cf5a4ef in QAction::activate (this=0x10b6e10, event=<value optimized out>) at kernel/qaction.cpp:1160
#41 0x00007fc77d2c3fea in QAbstractButtonPrivate::click (this=0x1050d10) at widgets/qabstractbutton.cpp:525
#42 0x00007fc77d2c4275 in QAbstractButton::mouseReleaseEvent (this=0x1050a70, e=0x7fff7eef4830) at widgets/qabstractbutton.cpp:1115
#43 0x00007fc77d392cba in QToolButton::mouseReleaseEvent (this=0x2bd7360, e=0x0) at widgets/qtoolbutton.cpp:709
#44 0x00007fc77cfad9c0 in QWidget::event (this=0x1050a70, event=0x7fff7eef4830) at kernel/qwidget.cpp:7549
#45 0x00007fc77cf5eefc in QApplicationPrivate::notify_helper (this=0xd2a8c0, receiver=0x1050a70, e=0x7fff7eef4830) at kernel/qapplication.cpp:4056
#46 0x00007fc77cf66011 in QApplication::notify (this=<value optimized out>, receiver=0x1050a70, e=0x7fff7eef4830) at kernel/qapplication.cpp:3758
#47 0x00007fc77db95e56 in KApplication::notify (this=0x7fff7eef6750, receiver=0x1050a70, event=0x7fff7eef4830) at ../../kdeui/kernel/kapplication.cpp:302
#48 0x00007fc77c63ac2c in QCoreApplication::notifyInternal (this=0x7fff7eef6750, receiver=0x1050a70, event=0x7fff7eef4830) at kernel/qcoreapplication.cpp:610
#49 0x00007fc77cf658e0 in QCoreApplication::sendSpontaneousEvent (receiver=0x1050a70, event=0x7fff7eef4830, alienWidget=0x1050a70, nativeWidget=0xd40200, buttonDown=<value optimized out>, 
    lastMouseReceiver=<value optimized out>) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:216
#50 QApplicationPrivate::sendMouseEvent (receiver=0x1050a70, event=0x7fff7eef4830, alienWidget=0x1050a70, nativeWidget=0xd40200, buttonDown=<value optimized out>, 
    lastMouseReceiver=<value optimized out>) at kernel/qapplication.cpp:2924
#51 0x00007fc77cfcba0e in QETWidget::translateMouseEvent (this=0xd40200, event=<value optimized out>) at kernel/qapplication_x11.cpp:4409
#52 0x00007fc77cfcaaa9 in QApplication::x11ProcessEvent (this=<value optimized out>, event=0x7fff7eef6360) at kernel/qapplication_x11.cpp:3550
#53 0x00007fc77cff3d0c in x11EventSourceDispatch (s=<value optimized out>, callback=<value optimized out>, user_data=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:146
#54 0x00007fc775eb4bce in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#55 0x00007fc775eb8598 in ?? () from /lib/libglib-2.0.so.0
#56 0x00007fc775eb86c0 in g_main_context_iteration () from /lib/libglib-2.0.so.0
#57 0x00007fc77c6631a6 in QEventDispatcherGlib::processEvents (this=0xd02cb0, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:327
#58 0x00007fc77cff34be in QGuiEventDispatcherGlib::processEvents (this=0x2bd7360, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:202
#59 0x00007fc77c639532 in QEventLoop::processEvents (this=<value optimized out>, flags=) at kernel/qeventloop.cpp:149
#60 0x00007fc77c639904 in QEventLoop::exec (this=0x7fff7eef6690, flags=) at kernel/qeventloop.cpp:201
#61 0x00007fc77c63bab9 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#62 0x0000000000403f47 in _start ()

Reported using DrKonqi