Application: systemsettings (1.0)
KDE Platform Version: 4.4.1 (KDE 4.4.1)
Qt Version: 4.6.2
Operating System: Linux 2.6.32-17-generic i686
Distribution: Ubuntu lucid (development branch)

-- Information about the crash:
I had the System Settings - Add and remove Software - Software updates window open, and I noticed that the 5 updates it suggested were listed as "The following packages have been kept back" by apt-get upgrade.
So I left the window open and issued
sudo apt-get update && sudo apt-get upgrade
from Konsole. It is possible that there was a lock problem on the apt cache, since after a while the System settings applet crashed.
This is with Kubuntu 10.04

 -- Backtrace:
Application: System Settings (systemsettings), signal: Segmentation fault
[Current thread is 1 (Thread 0xb7779760 (LWP 1297))]

Thread 2 (Thread 0xb4fceb70 (LWP 1367)):
#0  0x04b0b45c in g_main_context_iteration () from /lib/libglib-2.0.so.0
#1  0x0656c60f in QEventDispatcherGlib::processEvents (this=0x95e1ee0, flags=...) at kernel/qeventdispatcher_glib.cpp:414
#2  0x0653f059 in QEventLoop::processEvents (this=0xb4fce240, flags=) at kernel/qeventloop.cpp:149
#3  0x0653f4aa in QEventLoop::exec (this=0xb4fce240, flags=...) at kernel/qeventloop.cpp:201
#4  0x0643b5a8 in QThread::exec (this=0x9564398) at thread/qthread.cpp:487
#5  0x0651ec1b in QInotifyFileSystemWatcherEngine::run (this=0x9564398) at io/qfilesystemwatcher_inotify.cpp:248
#6  0x0643e32e in QThreadPrivate::start (arg=0x9564398) at thread/qthread_unix.cpp:248
#7  0x00e1296e in start_thread () from /lib/tls/i686/cmov/libpthread.so.0
#8  0x00c2a9de in clone () from /lib/tls/i686/cmov/libc.so.6

Thread 1 (Thread 0xb7779760 (LWP 1297)):
[KCrash Handler]
#6  0x0655465b in QObjectPrivate::isSignalConnected (sender=0x9732518, m=0x85c7cc4, local_signal_index=11, argv=0xbf9304b4) at kernel/qobject_p.h:227
#7  QMetaObject::activate (sender=0x9732518, m=0x85c7cc4, local_signal_index=11, argv=0xbf9304b4) at kernel/qobject.cpp:3218
#8  0x085a0e19 in PackageKit::Transaction::finished(PackageKit::Transaction::ExitStatus, unsigned int) () from /usr/lib/libpackagekit-qt.so.12
#9  0x0859b37c in PackageKit::ClientPrivate::serviceOwnerChanged(QString const&, QString const&, QString const&) () from /usr/lib/libpackagekit-qt.so.12
#10 0x0859d453 in PackageKit::ClientPrivate::qt_metacall(QMetaObject::Call, int, void**) () from /usr/lib/libpackagekit-qt.so.12
#11 0x06545c9a in QMetaObject::metacall (object=0x9681d20, cl=13, idx=6, argv=0xbf930640) at kernel/qmetaobject.cpp:237
#12 0x065543d5 in QMetaObject::activate (sender=0x9683980, m=0x79ec88, local_signal_index=2, argv=0xbf930640) at kernel/qobject.cpp:3293
#13 0x00786d9f in QDBusConnectionInterface::serviceOwnerChanged (this=0x9683980, _t1=..., _t2=..., _t3=...) at .moc/release-shared/moc_qdbusconnectioninterface.cpp:210
#14 0x007870c3 in QDBusConnectionInterface::qt_metacall (this=0x9683980, _c=QMetaObject::InvokeMetaMethod, _id=2, _a=0xbf930810) at .moc/release-shared/moc_qdbusconnectioninterface.cpp:137
#15 0x06545c9a in QMetaObject::metacall (object=0x9683980, cl=13, idx=7, argv=0xbf930810) at kernel/qmetaobject.cpp:237
#16 0x065543d5 in QMetaObject::activate (sender=0x9683980, m=0x79ec88, local_signal_index=6, argv=0xbf930810) at kernel/qobject.cpp:3293
#17 0x00786c4f in QDBusConnectionInterface::NameOwnerChanged (this=0x9683980, _t1=..., _t2=..., _t3=...) at .moc/release-shared/moc_qdbusconnectioninterface.cpp:238
#18 0x00787153 in QDBusConnectionInterface::qt_metacall (this=0x9683980, _c=QMetaObject::InvokeMetaMethod, _id=6, _a=0xbf930a1c) at .moc/release-shared/moc_qdbusconnectioninterface.cpp:141
#19 0x00747b34 in QDBusConnectionPrivate::deliverCall (this=0x9681f70, object=0x9683980, msg=..., metaTypes=..., slotIdx=11) at qdbusintegrator.cpp:904
#20 0x00752ea7 in QDBusCallDeliveryEvent::placeMetaCall (this=0x93a84c0, object=0x9683980) at qdbusintegrator_p.h:101
#21 0x065513fe in QObject::event (this=0x9683980, e=0x93a84c0) at kernel/qobject.cpp:1248
#22 0x010ce4dc in QApplicationPrivate::notify_helper (this=0x92f43e8, receiver=0x9683980, e=0x93a84c0) at kernel/qapplication.cpp:4300
#23 0x010d505e in QApplication::notify (this=0xbf9312ec, receiver=0x9683980, e=0x93a84c0) at kernel/qapplication.cpp:3704
#24 0x002eff3a in KApplication::notify (this=0xbf9312ec, receiver=0x9683980, event=0x93a84c0) at ../../kdeui/kernel/kapplication.cpp:302
#25 0x06540a3b in QCoreApplication::notifyInternal (this=0xbf9312ec, receiver=0x9683980, event=0x93a84c0) at kernel/qcoreapplication.cpp:704
#26 0x06543473 in QCoreApplication::sendEvent (receiver=0x0, event_type=0, data=0x92d6340) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:215
#27 QCoreApplicationPrivate::sendPostedEvents (receiver=0x0, event_type=0, data=0x92d6340) at kernel/qcoreapplication.cpp:1345
#28 0x065435dd in QCoreApplication::sendPostedEvents (receiver=0x0, event_type=0) at kernel/qcoreapplication.cpp:1238
#29 0x0656cadf in QCoreApplication::sendPostedEvents (s=0x92f6510) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:220
#30 postEventSourceDispatch (s=0x92f6510) at kernel/qeventdispatcher_glib.cpp:276
#31 0x04b075e5 in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#32 0x04b0b2d8 in ?? () from /lib/libglib-2.0.so.0
#33 0x04b0b4b8 in g_main_context_iteration () from /lib/libglib-2.0.so.0
#34 0x0656c5d5 in QEventDispatcherGlib::processEvents (this=0x92d6520, flags=...) at kernel/qeventdispatcher_glib.cpp:412
#35 0x0118dfd5 in QGuiEventDispatcherGlib::processEvents (this=0x92d6520, flags=...) at kernel/qguieventdispatcher_glib.cpp:204
#36 0x0653f059 in QEventLoop::processEvents (this=0xbf931244, flags=) at kernel/qeventloop.cpp:149
#37 0x0653f4aa in QEventLoop::exec (this=0xbf931244, flags=...) at kernel/qeventloop.cpp:201
#38 0x0654369f in QCoreApplication::exec () at kernel/qcoreapplication.cpp:981
#39 0x010ce577 in QApplication::exec () at kernel/qapplication.cpp:3579
#40 0x08056b5e in main (argc=3, argv=0xbf931434) at ../../../systemsettings/app/main.cpp:49

Reported using DrKonqi