This bug was also reported to us downstream at Launchpad. It turned out to be a duplicate of another bug that nobody got around to forwarding here...

Anyway, the bug, https://launchpad.net/bugs/384983 has an almost-complete backtrace which is just missing a few lines from the KIO libs. It would be nice if you could install kdepim-dbg and get a new backtrace, preferrably with KDE 4.2.4 if possible: (http://www.kubuntu.org/news/kde-4.2.4)

Here's the backtrace.

Applicazione: Kontact (kontact), segnale SIGSEGV
[Current thread is 0 (LWP 4805)]

Thread 2 (Thread 0xb02bfb90 (LWP 4904)):
#0  0xb8016430 in __kernel_vsyscall ()
#1  0xb5164412 in pthread_cond_timedwait@@GLIBC_2.3.2 () from /lib/tls/i686/cmov/libpthread.so.0
#2  0xb597e344 in pthread_cond_timedwait () from /lib/tls/i686/cmov/libc.so.6
#3  0xb5b6a98c in QWaitCondition::wait () from /usr/lib/libQtCore.so.4
#4  0xb5b5fe76 in ?? () from /usr/lib/libQtCore.so.4
#5  0xb5b6996e in ?? () from /usr/lib/libQtCore.so.4
#6  0xb51604ff in start_thread () from /lib/tls/i686/cmov/libpthread.so.0
#7  0xb596f49e in clone () from /lib/tls/i686/cmov/libc.so.6

Thread 1 (Thread 0xb487a700 (LWP 4805)):
[KCrash Handler]
#6  0xb730adfc in KCal::IncidenceBase::uid () from /usr/lib/libkcal.so.4
#7  0xb738f659 in KCal::ResourceCached::clearChange () from /usr/lib/libkcal.so.4
#8  0xaf9f7374 in KCal::ResourceRemote::slotSaveJobResult () from /usr/lib/libkcal_resourceremote.so.4
#9  0xaf9f7887 in KCal::ResourceRemote::qt_metacall () from /usr/lib/libkcal_resourceremote.so.4
#10 0xb5c73ca8 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#11 0xb5c74932 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#12 0xb5e97b93 in KJob::result () from /usr/lib/libkdecore.so.5
#13 0xb5e98039 in KJob::emitResult () from /usr/lib/libkdecore.so.5
#14 0xb6fc4838 in KIO::FileCopyJob::slotResult () from /usr/lib/libkio.so.5
#15 0xb6fc1a8f in KIO::FileCopyJob::qt_metacall () from /usr/lib/libkio.so.5
#16 0xb5c73ca8 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#17 0xb5c74932 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#18 0xb5e97b93 in KJob::result () from /usr/lib/libkdecore.so.5
#19 0xb5e98039 in KJob::emitResult () from /usr/lib/libkdecore.so.5
#20 0xb6fbeab5 in KIO::SimpleJob::slotFinished () from /usr/lib/libkio.so.5
#21 0xb6fbfd23 in KIO::TransferJob::slotFinished () from /usr/lib/libkio.so.5
#22 0xb6fc0e0b in KIO::TransferJob::qt_metacall () from /usr/lib/libkio.so.5
#23 0xb5c73ca8 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#24 0xb5c74932 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#25 0xb707d107 in KIO::SlaveInterface::finished () from /usr/lib/libkio.so.5
#26 0xb7080e47 in KIO::SlaveInterface::dispatch () from /usr/lib/libkio.so.5
#27 0xb707d5e7 in KIO::SlaveInterface::dispatch () from /usr/lib/libkio.so.5
#28 0xb706d98d in KIO::Slave::gotInput () from /usr/lib/libkio.so.5
#29 0xb706fee3 in KIO::Slave::qt_metacall () from /usr/lib/libkio.so.5
#30 0xb5c73ca8 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#31 0xb5c74932 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#32 0xb6f84ea7 in KIO::Connection::readyRead () from /usr/lib/libkio.so.5
#33 0xb6f86813 in ?? () from /usr/lib/libkio.so.5
#34 0xb6f86bf6 in KIO::Connection::qt_metacall () from /usr/lib/libkio.so.5
#35 0xb5c6c8fb in QMetaCallEvent::placeMetaCall () from /usr/lib/libQtCore.so.4
#36 0xb5c6e3a0 in QObject::event () from /usr/lib/libQtCore.so.4
#37 0xb612ce9c in QApplicationPrivate::notify_helper () from /usr/lib/libQtGui.so.4
#38 0xb613519e in QApplication::notify () from /usr/lib/libQtGui.so.4
#39 0xb6d50e0d in KApplication::notify () from /usr/lib/libkdeui.so.5
#40 0xb5c5da3b in QCoreApplication::notifyInternal () from /usr/lib/libQtCore.so.4
#41 0xb5c5e695 in QCoreApplicationPrivate::sendPostedEvents () from /usr/lib/libQtCore.so.4
#42 0xb5c5e88d in QCoreApplication::sendPostedEvents () from /usr/lib/libQtCore.so.4
#43 0xb5c897ef in ?? () from /usr/lib/libQtCore.so.4
#44 0xb4d30b88 in IA__g_main_context_dispatch (context=0x902aa90) at /build/buildd/glib2.0-2.20.1/glib/gmain.c:1814
#45 0xb4d340eb in g_main_context_iterate (context=0x902aa90, block=1, dispatch=1, self=0x9028570) at /build/buildd/glib2.0-2.20.1/glib/gmain.c:2448
#46 0xb4d34268 in IA__g_main_context_iteration (context=0x902aa90, may_block=1) at /build/buildd/glib2.0-2.20.1/glib/gmain.c:2511
#47 0xb5c89438 in QEventDispatcherGlib::processEvents () from /usr/lib/libQtCore.so.4
#48 0xb61ce365 in ?? () from /usr/lib/libQtGui.so.4
#49 0xb5c5c06a in QEventLoop::processEvents () from /usr/lib/libQtCore.so.4
#50 0xb5c5c4aa in QEventLoop::exec () from /usr/lib/libQtCore.so.4
#51 0xb6647403 in QDialog::exec () from /usr/lib/libQtGui.so.4
#52 0xb6ccd114 in KMessageBox::createKMessageBox () from /usr/lib/libkdeui.so.5
#53 0xb6cce491 in KMessageBox::createKMessageBox () from /usr/lib/libkdeui.so.5
#54 0xb6ccf283 in KMessageBox::errorListWId () from /usr/lib/libkdeui.so.5
#55 0xb6ccf4a1 in KMessageBox::error () from /usr/lib/libkdeui.so.5
#56 0xaf8bdf78 in CalendarView::showErrorMessage () from /usr/lib/libkorganizerprivate.so.4
#57 0xaf8c99dc in CalendarView::qt_metacall () from /usr/lib/libkorganizerprivate.so.4
#58 0xb5c73ca8 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#59 0xb5c74932 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#60 0xb7396e83 in KCal::CalendarResources::signalErrorMessage () from /usr/lib/libkcal.so.4
#61 0xb7396eb4 in KCal::CalendarResources::slotSaveError () from /usr/lib/libkcal.so.4
#62 0xb739717b in KCal::CalendarResources::qt_metacall () from /usr/lib/libkcal.so.4
#63 0xb5c73ca8 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#64 0xb5c74932 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#65 0xb7383da9 in KCal::ResourceCalendar::resourceSaveError () from /usr/lib/libkcal.so.4
#66 0xb73847b3 in KCal::ResourceCalendar::saveError () from /usr/lib/libkcal.so.4
#67 0xb73933f7 in KCal::ResourceCached::save () from /usr/lib/libkcal.so.4
#68 0xb739359c in KCal::ResourceCached::slotSave () from /usr/lib/libkcal.so.4
#69 0xb73936c3 in KCal::ResourceCached::qt_metacall () from /usr/lib/libkcal.so.4
#70 0xaf9f77fa in KCal::ResourceRemote::qt_metacall () from /usr/lib/libkcal_resourceremote.so.4
#71 0xb5c73ca8 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#72 0xb5c74932 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#73 0xb5caf717 in QTimer::timeout () from /usr/lib/libQtCore.so.4
#74 0xb5c796fe in QTimer::timerEvent () from /usr/lib/libQtCore.so.4
#75 0xb5c6e15f in QObject::event () from /usr/lib/libQtCore.so.4
#76 0xb612ce9c in QApplicationPrivate::notify_helper () from /usr/lib/libQtGui.so.4
#77 0xb613519e in QApplication::notify () from /usr/lib/libQtGui.so.4
#78 0xb6d50e0d in KApplication::notify () from /usr/lib/libkdeui.so.5
#79 0xb5c5da3b in QCoreApplication::notifyInternal () from /usr/lib/libQtCore.so.4
#80 0xb5c8cd71 in ?? () from /usr/lib/libQtCore.so.4
#81 0xb5c894e0 in ?? () from /usr/lib/libQtCore.so.4
#82 0xb4d30b88 in IA__g_main_context_dispatch (context=0x902aa90) at /build/buildd/glib2.0-2.20.1/glib/gmain.c:1814
#83 0xb4d340eb in g_main_context_iterate (context=0x902aa90, block=1, dispatch=1, self=0x9028570) at /build/buildd/glib2.0-2.20.1/glib/gmain.c:2448
#84 0xb4d34268 in IA__g_main_context_iteration (context=0x902aa90, may_block=1) at /build/buildd/glib2.0-2.20.1/glib/gmain.c:2511
#85 0xb5c89438 in QEventDispatcherGlib::processEvents () from /usr/lib/libQtCore.so.4
#86 0xb61ce365 in ?? () from /usr/lib/libQtGui.so.4
#87 0xb5c5c06a in QEventLoop::processEvents () from /usr/lib/libQtCore.so.4
#88 0xb5c5c4aa in QEventLoop::exec () from /usr/lib/libQtCore.so.4
#89 0xb5c5e959 in QCoreApplication::exec () from /usr/lib/libQtCore.so.4
#90 0xb612cd17 in QApplication::exec () from /usr/lib/libQtGui.so.4
#91 0x0804c072 in _start ()