Jonathan, I've got the same symptoms (since upgrading to maverick last week) so I imagine my backtrace does little more than duplicate Konrad's, but here it is anyway.


Application: Plasma Workspace (plasma-desktop), signal: Segmentation fault
[Current thread is 1 (Thread 0x7ff46528e780 (LWP 8128))]

Thread 2 (Thread 0x7ff4445ba710 (LWP 8132)):
#0  0x00007ff464ba1203 in __poll (fds=<value optimized out>, nfds=<value optimized out>, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:87
#1  0x00007ff45981f009 in g_main_context_poll (context=0x1c048d0, block=<value optimized out>, dispatch=<value optimized out>, self=<value optimized out>) at /build/buildd/glib2.0-2.26.0/glib/gmain.c:3093
#2  g_main_context_iterate (context=0x1c048d0, block=<value optimized out>, dispatch=<value optimized out>, self=<value optimized out>) at /build/buildd/glib2.0-2.26.0/glib/gmain.c:2775
#3  0x00007ff45981f45c in g_main_context_iteration (context=0x1c048d0, may_block=1) at /build/buildd/glib2.0-2.26.0/glib/gmain.c:2843
#4  0x00007ff4622561e6 in QEventDispatcherGlib::processEvents (this=0x1ab3660, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:417
#5  0x00007ff462228a02 in QEventLoop::processEvents (this=<value optimized out>, flags=) at kernel/qeventloop.cpp:149
#6  0x00007ff462228dec in QEventLoop::exec (this=0x7ff4445b9d90, flags=) at kernel/qeventloop.cpp:201
#7  0x00007ff4621332fd in QThread::exec (this=<value optimized out>) at thread/qthread.cpp:490
#8  0x00007ff4622085f8 in QInotifyFileSystemWatcherEngine::run (this=0x1b8f450) at io/qfilesystemwatcher_inotify.cpp:248
#9  0x00007ff46213627e in QThreadPrivate::start (arg=0x1b8f450) at thread/qthread_unix.cpp:266
#10 0x00007ff461eab971 in start_thread (arg=<value optimized out>) at pthread_create.c:304
#11 0x00007ff464bad94d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#12 0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7ff46528e780 (LWP 8128)):
[KCrash Handler]
#6  findActionItemForAction (this=0x22e5600, event=<value optimized out>) at /build/buildd/plasma-widget-message-indicator-0.5.6/src/listenermodel.cpp:189
#7  removeAction (this=0x22e5600, event=<value optimized out>) at /build/buildd/plasma-widget-message-indicator-0.5.6/src/listenermodel.cpp:177
#8  ServerItem::eventFilter (this=0x22e5600, event=<value optimized out>) at /build/buildd/plasma-widget-message-indicator-0.5.6/src/listenermodel.cpp:150
#9  0x00007ff462229507 in QCoreApplicationPrivate::sendThroughObjectEventFilters (this=<value optimized out>, receiver=0x278ed00, event=0x7fffc1681e90) at kernel/qcoreapplication.cpp:847
#10 0x00007ff461373fac in QApplicationPrivate::notify_helper (this=0x126bbb0, receiver=0x278ed00, e=0x7fffc1681e90) at kernel/qapplication.cpp:4392
#11 0x00007ff461379aed in QApplication::notify (this=0x1254660, receiver=0x278ed00, e=0x7fffc1681e90) at kernel/qapplication.cpp:4277
#12 0x00007ff462ec5156 in KApplication::notify (this=0x1254660, receiver=0x278ed00, event=0x7fffc1681e90) at ../../kdeui/kernel/kapplication.cpp:310
#13 0x00007ff462229cdc in QCoreApplication::notifyInternal (this=0x1254660, receiver=0x278ed00, event=0x7fffc1681e90) at kernel/qcoreapplication.cpp:732
#14 0x00007ff4613bfbf1 in sendEvent (this=0x278ed00, action=0x265f900) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:215
#15 QWidget::removeAction (this=0x278ed00, action=0x265f900) at kernel/qwidget.cpp:3169
#16 0x00007ff4617d4350 in QMenu::clear (this=<value optimized out>) at widgets/qmenu.cpp:1714
#17 0x00007ff45ab42324 in DBusMenuImporter::GetChildrenCallback(int, QDBusPendingCallWatcher*) () from /usr/lib/libdbusmenu-qt.so.2
#18 0x00007ff45ab41315 in DBusMenuImporter::dispatch(QDBusPendingCallWatcher*) () from /usr/lib/libdbusmenu-qt.so.2
#19 0x00007ff45ab459dc in DBusMenuImporter::qt_metacall(QMetaObject::Call, int, void**) () from /usr/lib/libdbusmenu-qt.so.2
#20 0x00007ff462241b27 in QMetaObject::activate (sender=0x1d8a4c0, m=<value optimized out>, local_signal_index=<value optimized out>, argv=0x1) at kernel/qobject.cpp:3280
#21 0x00007ff4625ba37f in QDBusPendingCallWatcher::finished (this=0x22e5600, _t1=0x1d8a4c0) at .moc/release-shared/moc_qdbuspendingcall.cpp:92
#22 0x00007ff4625ba409 in _q_finished (this=0x1d8a4c0, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0x257b640) at qdbuspendingcall.cpp:482
#23 QDBusPendingCallWatcher::qt_metacall (this=0x1d8a4c0, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0x257b640) at .moc/release-shared/moc_qdbuspendingcall.cpp:80
#24 0x00007ff46223bbde in QObject::event (this=0x1d8a4c0, e=0x22e5600) at kernel/qobject.cpp:1219
#25 0x00007ff461373fdc in QApplicationPrivate::notify_helper (this=0x126bbb0, receiver=0x1d8a4c0, e=0x2754e20) at kernel/qapplication.cpp:4396
#26 0x00007ff461379aed in QApplication::notify (this=0x1254660, receiver=0x1d8a4c0, e=0x2754e20) at kernel/qapplication.cpp:4277
#27 0x00007ff462ec5156 in KApplication::notify (this=0x1254660, receiver=0x1d8a4c0, event=0x2754e20) at ../../kdeui/kernel/kapplication.cpp:310
#28 0x00007ff462229cdc in QCoreApplication::notifyInternal (this=0x1254660, receiver=0x1d8a4c0, event=0x2754e20) at kernel/qcoreapplication.cpp:732
#29 0x00007ff46222cc22 in sendEvent (receiver=0x0, event_type=<value optimized out>, data=0x1239560) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:215
#30 QCoreApplicationPrivate::sendPostedEvents (receiver=0x0, event_type=<value optimized out>, data=0x1239560) at kernel/qcoreapplication.cpp:1373
#31 0x00007ff462256653 in sendPostedEvents (s=0x126f250) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:220
#32 postEventSourceDispatch (s=0x126f250) at kernel/qeventdispatcher_glib.cpp:277
#33 0x00007ff45981b342 in g_main_dispatch (context=0x126e1f0) at /build/buildd/glib2.0-2.26.0/glib/gmain.c:2149
#34 g_main_context_dispatch (context=0x126e1f0) at /build/buildd/glib2.0-2.26.0/glib/gmain.c:2702
#35 0x00007ff45981f2a8 in g_main_context_iterate (context=0x126e1f0, block=<value optimized out>, dispatch=<value optimized out>, self=<value optimized out>) at /build/buildd/glib2.0-2.26.0/glib/gmain.c:2780
#36 0x00007ff45981f45c in g_main_context_iteration (context=0x126e1f0, may_block=1) at /build/buildd/glib2.0-2.26.0/glib/gmain.c:2843
#37 0x00007ff462256193 in QEventDispatcherGlib::processEvents (this=0x1239070, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:415
#38 0x00007ff461426a4e in QGuiEventDispatcherGlib::processEvents (this=0x22e5600, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:204
#39 0x00007ff462228a02 in QEventLoop::processEvents (this=<value optimized out>, flags=) at kernel/qeventloop.cpp:149
#40 0x00007ff462228dec in QEventLoop::exec (this=0x7fffc1682cc0, flags=) at kernel/qeventloop.cpp:201
#41 0x00007ff46222cebb in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1009
#42 0x00007ff464e84a56 in kdemain (argc=<value optimized out>, argv=<value optimized out>) at ../../../../plasma/desktop/shell/main.cpp:118
#43 0x00007ff464ae5d8e in __libc_start_main (main=<value optimized out>, argc=<value optimized out>, ubp_av=<value optimized out>, init=<value optimized out>, fini=<value optimized out>, rtld_fini=<value optimized out>, stack_end=0x7fffc1683088) at libc-start.c:226
#44 0x0000000000400669 in _start ()