Version:           ?? for now - I can't see it because of the crash (using Devel)
OS:                Linux
Installed from:    Compiled sources

The package was sourced from:
deb http://ppa.launchpad.net/kubuntu-experimental/ubuntu intrepid main

As given in:
http://www.kubuntu.org/news/kde-4.2-beta-2

The application crashes shortly after logging in, giving the following trace, and remains running as a background task.

This is the backtrace from the KDE crash handler, GDB report follows:

Application: Kontact (kontact), signal SIGABRT

Thread 1 (Thread 0xb4ba36c0 (LWP 15590)):
[KCrash Handler]
#6  0xb80d3430 in __kernel_vsyscall ()
#7  0xb593f880 in raise () from /lib/tls/i686/cmov/libc.so.6
#8  0xb5941248 in abort () from /lib/tls/i686/cmov/libc.so.6
#9  0xb5be5795 in qt_message_output () from /usr/lib/libQtCore.so.4
#10 0xb5be5872 in qFatal () from /usr/lib/libQtCore.so.4
#11 0xb5be5915 in qt_assert () from /usr/lib/libQtCore.so.4
#12 0xb6faf08e in KDBusServiceStarter (this=0x9c4ac40) at /build/buildd/kde4libs-4.1.85/kio/kio/kdbusservicestarter.cpp:54
#13 0xb796c96c in MainWindow (this=0x9caf638) at /build/buildd/kdepim-4.1.85/kontact/src/mainwindow.cpp:107
#14 0x0804acee in KontactApp::newInstance (this=0xbfed3688) at /build/buildd/kdepim-4.1.85/kontact/src/main.cpp:134
#15 0xb6be1b76 in KUniqueApplicationAdaptor::newInstance (this=0x9864cc0, asn_id=@0x98dbe48, args=@0x9c09ea8) at /build/buildd/kde4libs-4.1.85/kdeui/kernel/kuniqueapplication_p.h:77
#16 0xb6bdfd3e in KUniqueApplicationAdaptor::qt_metacall (this=0x9864cc0, _c=QMetaObject::InvokeMetaMethod, _id=0, _a=0xbfed10e8)
    at /build/buildd/kde4libs-4.1.85/obj-i486-linux-gnu/kdeui/kuniqueapplication_p.moc:74
#17 0xb5de626e in ?? () from /usr/lib/libQtDBus.so.4
#18 0xb5de74a7 in ?? () from /usr/lib/libQtDBus.so.4
#19 0xb5de79b1 in ?? () from /usr/lib/libQtDBus.so.4
#20 0xb5de7eaa in ?? () from /usr/lib/libQtDBus.so.4
#21 0xb5ced771 in QObject::event () from /usr/lib/libQtCore.so.4
#22 0xb5cdd7cb in QCoreApplication::event () from /usr/lib/libQtCore.so.4
#23 0xb6203206 in QApplication::event () from /usr/lib/libQtGui.so.4
#24 0xb61fd8ec in QApplicationPrivate::notify_helper () from /usr/lib/libQtGui.so.4
#25 0xb620572e in QApplication::notify () from /usr/lib/libQtGui.so.4
#26 0xb6bd7d3d in KApplication::notify (this=0xbfed3688, receiver=0xbfed3688, event=0x9c49cf0) at /build/buildd/kde4libs-4.1.85/kdeui/kernel/kapplication.cpp:307
#27 0xb5cdde61 in QCoreApplication::notifyInternal () from /usr/lib/libQtCore.so.4
#28 0xb5cdeae5 in QCoreApplicationPrivate::sendPostedEvents () from /usr/lib/libQtCore.so.4
#29 0xb5cdecdd in QCoreApplication::sendPostedEvents () from /usr/lib/libQtCore.so.4
#30 0xb5d0882f in ?? () from /usr/lib/libQtCore.so.4
#31 0xb4f896f8 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#32 0xb4f8cda3 in ?? () from /usr/lib/libglib-2.0.so.0
#33 0xb4f8cf61 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#34 0xb5d08478 in QEventDispatcherGlib::processEvents () from /usr/lib/libQtCore.so.4
#35 0xb6297ea5 in ?? () from /usr/lib/libQtGui.so.4
#36 0xb5cdc52a in QEventLoop::processEvents () from /usr/lib/libQtCore.so.4
#37 0xb5cdc6ea in QEventLoop::exec () from /usr/lib/libQtCore.so.4
#38 0xb666a987 in QDialog::exec () from /usr/lib/libQtGui.so.4
#39 0xb6b50fac in KMessageBox::createKMessageBox (dialog=0x9ca2b58, icon=@0xbfed1c38, text=@0xbfed1f4c, strlist=@0xbfed1d88, ask=@0xbfed1cc0, checkboxReturn=0xbfed1cfb, options={i = -1074979788}, 
    details=@0xbfed1cb8, notifyType=QMessageBox::Warning) at /build/buildd/kde4libs-4.1.85/kdeui/dialogs/kmessagebox.cpp:330
#40 0xb6b52431 in KMessageBox::createKMessageBox (dialog=0x9ca2b58, icon=QMessageBox::Warning, text=@0xbfed1f4c, strlist=@0xbfed1d88, ask=@0xbfed1cc0, checkboxReturn=0xbfed1cfb, options=
      {i = -1074979652}, details=@0xbfed1cb8) at /build/buildd/kde4libs-4.1.85/kdeui/dialogs/kmessagebox.cpp:151
#41 0xb6b55266 in KMessageBox::warningYesNoListWId (parent_id=0, text=@0xbfed1f4c, strlist=@0xbfed1d88, caption=@0xbfed1f38, buttonYes_=@0xbfed1f24, buttonNo_=@0xbfed1f10, 
    dontAskAgainName=@0xbfed1f0c, options={i = -1074979520}) at /build/buildd/kde4libs-4.1.85/kdeui/dialogs/kmessagebox.cpp:624
#42 0xb6b55446 in KMessageBox::warningYesNoList (parent=0x0, text=@0xbfed1f4c, strlist=@0xbfed1d88, caption=@0xbfed1f38, buttonYes=@0xbfed1f24, buttonNo=@0xbfed1f10, dontAskAgainName=@0xbfed1f0c, 
    options={i = -1074979452}) at /build/buildd/kde4libs-4.1.85/kdeui/dialogs/kmessagebox.cpp:583
#43 0xb6b554bd in KMessageBox::warningYesNo (parent=0x0, text=@0xbfed1f4c, caption=@0xbfed1f38, buttonYes=@0xbfed1f24, buttonNo=@0xbfed1f10, dontAskAgainName=@0xbfed1f0c, options={i = -1074979064})
    at /build/buildd/kde4libs-4.1.85/kdeui/dialogs/kmessagebox.cpp:560
#44 0xb1681286 in KMail::lockOrDie () at /build/buildd/kdepim-4.1.85/kmail/kmstartup.cpp:227
#45 0xb1acd299 in KMailPart (this=0x9c45220, parentWidget=0x98dde98, parent=0x98dde98) at /build/buildd/kdepim-4.1.85/kmail/kmail_part.cpp:69
#46 0xb1acde65 in KPluginFactory::createPartInstance<KMailPart> (parentWidget=0x98dde98, parent=0x98dde98, args=@0xbfed3220) at /usr/include/kpluginfactory.h:467
#47 0xb60175ff in KPluginFactory::create (this=0x9c39280, iface=0xb718bc80 "KParts::ReadOnlyPart", parentWidget=0x98dde98, parent=0x98dde98, args=@0xbfed3220, keyword=@0xbfed3210)
    at /build/buildd/kde4libs-4.1.85/kdecore/util/kpluginfactory.cpp:191
#48 0xb79494a3 in Kontact::Core::createPart (this=0x98dde98, libname=0x9c31c40 "kmailpart") at /usr/include/kpluginfactory.h:491
#49 0xb794a667 in Kontact::Plugin::loadPart (this=0x9c1f650) at /build/buildd/kdepim-4.1.85/kontactinterfaces/plugin.cpp:148
#50 0xb1b345c5 in KMailPlugin::createPart (this=0x9c1f650) at /build/buildd/kdepim-4.1.85/kontact/plugins/kmail/kmail_plugin.cpp:170
#51 0xb794a5c2 in Kontact::Plugin::part (this=0x9c1f650) at /build/buildd/kdepim-4.1.85/kontactinterfaces/plugin.cpp:187
#52 0xb79686ac in Kontact::MainWindow::selectPlugin (this=0x98dde98, plugin=0x9c1f650) at /build/buildd/kdepim-4.1.85/kontact/src/mainwindow.cpp:752
#53 0xb79636ac in Kontact::MainWindow::loadSettings (this=0x98dde98) at /build/buildd/kdepim-4.1.85/kontact/src/mainwindow.cpp:924
#54 0xb796c52d in Kontact::MainWindow::initObject (this=0x98dde98) at /build/buildd/kdepim-4.1.85/kontact/src/mainwindow.cpp:226
#55 0xb796ca10 in MainWindow (this=0x98dde98) at /build/buildd/kdepim-4.1.85/kontact/src/mainwindow.cpp:162
#56 0x0804c1b4 in main (argc=3, argv=0xbfed3984) at /build/buildd/kdepim-4.1.85/kontact/src/main.cpp:210


And from GDB:

(gdb) run
Starting program: /usr/bin/kontact
[Thread debugging using libthread_db enabled]
[New Thread 0xb4b736c0 (LWP 19878)]
Calling appendChild() on a null node does nothing.
Calling appendChild() on a null node does nothing.
Calling appendChild() on a null node does nothing.
Calling appendChild() on a null node does nothing.
Calling appendChild() on a null node does nothing.
Calling appendChild() on a null node does nothing.
Calling appendChild() on a null node does nothing.
Calling appendChild() on a null node does nothing.
Calling appendChild() on a null node does nothing.
Calling appendChild() on a null node does nothing.
Calling appendChild() on a null node does nothing.
kontact(19897) Sonnet::Loader::loadPlugin: Successfully loaded plugin: "kspell_hspell.desktop"
kontact(19897) Sonnet::Loader::loadPlugin: Successfully loaded plugin: "kspell_enchant.desktop"
<unknown program name>(19878)/: Communication problem with  "kontact" , it probably crashed.
Error message was:  "org.freedesktop.DBus.Error.NoReply" : " "Did not receive a reply. Possible causes include: the remote application did notsend a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken." "


Program exited with code 0377.
(gdb) thread apply all backtrace
No registers.