Application that crashed: plasma-desktop
Version of the application: 0.3
KDE Version: 4.3.00 (KDE 4.3.0)
Qt Version: 4.5.2
Operating System: Linux 2.6.28-15-generic x86_64
Distribution: Ubuntu 9.04

What I was doing when the application crashed:
I cannot reproduce, but try to switch desktops and you will recognize a crash after a few tries. My backtrace is appended I hope...

 -- Backtrace:
Application: Plasma Workspace (kdeinit4), signal: Segmentation fault
[Current thread is 0 (LWP 5058)]

Thread 3 (Thread 0x7fe63a16e950 (LWP 5063)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:261
#1  0x00007fe65e53dd19 in QWaitCondition::wait (this=0x2a8aca0, mutex=0x2a8ac98, time=18446744073709551615) at thread/qwaitcondition_unix.cpp:87
#2  0x00007fe65d3c781c in QHostInfoAgent::run (this=0x2a8ac80) at kernel/qhostinfo.cpp:260
#3  0x00007fe65e53cd35 in QThreadPrivate::start (arg=0x2a8ac80) at thread/qthread_unix.cpp:188
#4  0x00007fe65a4363ba in start_thread (arg=<value optimized out>) at pthread_create.c:297
#5  0x00007fe65b01afcd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#6  0x0000000000000000 in ?? ()

Thread 2 (Thread 0x7fe630dc4950 (LWP 15515)):
#0  pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:217
#1  0x00007fe65e53c785 in thread_sleep (ti=0x7fe630dc3fb0) at thread/qthread_unix.cpp:297
#2  0x00007fe65e53c8ee in QThread::msleep (msecs=50) at thread/qthread_unix.cpp:323
#3  0x00007fe62f52e7ce in ?? () from /usr/lib/kde4/plasma_applet_cwp.so
#4  0x00007fe65e53cd35 in QThreadPrivate::start (arg=0x2c8c8b0) at thread/qthread_unix.cpp:188
#5  0x00007fe65a4363ba in start_thread (arg=<value optimized out>) at pthread_create.c:297
#6  0x00007fe65b01afcd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#7  0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7fe65eafd750 (LWP 5058)):
[KCrash Handler]
#5  AbstractTaskItem::basicPreferredSize (this=0x5718e00) at /build/buildd/kdebase-workspace-4.3.0/plasma/applets/tasks/tasks.h:92
#6  0x00007fe63f5f3d13 in TaskItemLayout::layoutItems (this=0x28dd390) at /build/buildd/kdebase-workspace-4.3.0/plasma/applets/tasks/taskitemlayout.cpp:273
#7  0x00007fe63f5f47f4 in TaskItemLayout::insert (this=0x28dd390, index=3, item=0x253da60) at /build/buildd/kdebase-workspace-4.3.0/plasma/applets/tasks/taskitemlayout.cpp:125
#8  0x00007fe63f5f49d0 in TaskItemLayout::addTaskItem (this=0x28dd390, item=0x253da60) at /build/buildd/kdebase-workspace-4.3.0/plasma/applets/tasks/taskitemlayout.cpp:82
#9  0x00007fe63f600468 in TaskGroupItem::itemAdded (this=0x2916fa0, groupableItem=0x6709c10) at /build/buildd/kdebase-workspace-4.3.0/plasma/applets/tasks/taskgroupitem.cpp:477
#10 0x00007fe63f600a5c in TaskGroupItem::qt_metacall (this=0x2916fa0, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0x7fff66b360e0)
    at /build/buildd/kdebase-workspace-4.3.0/obj-x86_64-linux-gnu/plasma/applets/tasks/taskgroupitem.moc:113
#11 0x00007fe65e63bea2 in QMetaObject::activate (sender=0x28d9c90, from_signal_index=<value optimized out>, to_signal_index=21, argv=0x0) at kernel/qobject.cpp:3113
#12 0x00007fe63fa3bcbf in TaskManager::TaskGroup::itemAdded (this=0x0, _t1=0x6709c10) at /build/buildd/kdebase-workspace-4.3.0/obj-x86_64-linux-gnu/libs/taskmanager/taskgroup.moc:139
#13 0x00007fe63fa3c81b in TaskManager::TaskGroup::add (this=0x28d9c90, item=0x6709c10) at /build/buildd/kdebase-workspace-4.3.0/libs/taskmanager/taskgroup.cpp:138
#14 0x00007fe63fa2b5e3 in TaskManager::ProgramGroupingStrategy::handleItem (this=0x25fadd0, item=0x6709c10)
    at /build/buildd/kdebase-workspace-4.3.0/libs/taskmanager/strategies/programgroupingstrategy.cpp:154
#15 0x00007fe63fa250bd in TaskManager::GroupManagerPrivate::addTask (this=0x2607d30, task={d = 0x7fff66b36250}) at /build/buildd/kdebase-workspace-4.3.0/libs/taskmanager/groupmanager.cpp:288
#16 0x00007fe63fa2734d in TaskManager::GroupManager::qt_metacall (this=0x25b7400, _c=<value optimized out>, _id=<value optimized out>, _a=0x7fff66b36380)
    at /build/buildd/kdebase-workspace-4.3.0/obj-x86_64-linux-gnu/libs/taskmanager/groupmanager.moc:103
#17 0x00007fe65e63bea2 in QMetaObject::activate (sender=0x2918d00, from_signal_index=<value optimized out>, to_signal_index=4, argv=0x0) at kernel/qobject.cpp:3113
#18 0x00007fe63fa3f152 in TaskManager::TaskManager::taskAdded (this=0x0, _t1=<value optimized out>) at /build/buildd/kdebase-workspace-4.3.0/obj-x86_64-linux-gnu/libs/taskmanager/taskmanager.moc:155
#19 0x00007fe63fa4112f in TaskManager::TaskManager::windowAdded (this=0x2918d00, w=42493971) at /build/buildd/kdebase-workspace-4.3.0/libs/taskmanager/taskmanager.cpp:262
#20 0x00007fe63fa4232f in TaskManager::TaskManager::qt_metacall (this=0x2918d00, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0x7fff66b36610)
    at /build/buildd/kdebase-workspace-4.3.0/obj-x86_64-linux-gnu/libs/taskmanager/taskmanager.moc:109
#21 0x00007fe65e63bea2 in QMetaObject::activate (sender=0x229de00, from_signal_index=<value optimized out>, to_signal_index=5, argv=0x0) at kernel/qobject.cpp:3113
#22 0x00007fe65ce31822 in KWindowSystem::windowAdded (this=0x0, _t1=42493971) at /build/buildd/kde4libs-4.3.0/obj-x86_64-linux-gnu/kdeui/kwindowsystem.moc:120
#23 0x00007fe65ce33b7c in KWindowSystemPrivate::addClient (this=0x223f560, w=42493971) at /build/buildd/kde4libs-4.3.0/kdeui/windowmanagement/kwindowsystem_x11.cpp:229
#24 0x00007fe65ce42557 in NETRootInfo::update (this=0x223f588, dirty_props=<value optimized out>) at /build/buildd/kde4libs-4.3.0/kdeui/windowmanagement/netwm.cpp:2186
#25 0x00007fe65ce4324b in NETRootInfo::event (this=0x223f588, event=<value optimized out>, properties=0x7fff66b36950, properties_size=5)
    at /build/buildd/kde4libs-4.3.0/kdeui/windowmanagement/netwm.cpp:2058
#26 0x00007fe65ce33ffb in KWindowSystemPrivate::x11Event (this=0x223f560, ev=0x7fff66b38380) at /build/buildd/kde4libs-4.3.0/kdeui/windowmanagement/kwindowsystem_x11.cpp:136
#27 0x00007fe65cd03b33 in KApplication::x11EventFilter (this=<value optimized out>, _event=0x7fff66b38380) at /build/buildd/kde4libs-4.3.0/kdeui/kernel/kapplication.cpp:911
#28 0x00007fe65257dbd7 in PlasmaApp::x11EventFilter (this=0x20050c0, event=0x7fff66b38380) at /build/buildd/kdebase-workspace-4.3.0/plasma/shells/desktop/plasmaapp.cpp:490
#29 0x00007fe65bc4e37f in qt_x11EventFilter (ev=0x7fff66b38380) at kernel/qapplication_x11.cpp:375
#30 0x00007fe65bc6187e in QApplication::x11ProcessEvent (this=0x20050c0, event=0x7fff66b38380) at kernel/qapplication_x11.cpp:3271
#31 0x00007fe65bc8b454 in x11EventSourceDispatch (s=0x2047540, callback=0, user_data=0x0) at kernel/qguieventdispatcher_glib.cpp:146
#32 0x00007fe65a68520a in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#33 0x00007fe65a6888e0 in ?? () from /usr/lib/libglib-2.0.so.0
#34 0x00007fe65a688a7c in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#35 0x00007fe65e64fa8f in QEventDispatcherGlib::processEvents (this=0x2043a70, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:327
#36 0x00007fe65bc8abdf in QGuiEventDispatcherGlib::processEvents (this=0x0, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:202
#37 0x00007fe65e624f42 in QEventLoop::processEvents (this=<value optimized out>, flags={i = 1723041392}) at kernel/qeventloop.cpp:149
#38 0x00007fe65e625314 in QEventLoop::exec (this=0x7fff66b386b0, flags={i = 1723041472}) at kernel/qeventloop.cpp:201
#39 0x00007fe65e6275e4 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#40 0x00007fe65256a6bb in kdemain (argc=1, argv=0x1ff7cd0) at /build/buildd/kdebase-workspace-4.3.0/plasma/shells/desktop/main.cpp:50
#41 0x0000000000407215 in launch (argc=1, _name=0x1ff84c8 "/usr/bin/plasma-desktop", args=<value optimized out>, cwd=0x0, envc=0, envs=0x1ff84e8 "", reset_env=false, tty=0x0, avoid_loops=false, 
    startup_id_str=0x40a3a1 "0") at /build/buildd/kde4libs-4.3.0/kinit/kinit.cpp:676
#42 0x0000000000407a38 in handle_launcher_request (sock=7, who=<value optimized out>) at /build/buildd/kde4libs-4.3.0/kinit/kinit.cpp:1168
#43 0x0000000000407fe5 in handle_requests (waitForPid=0) at /build/buildd/kde4libs-4.3.0/kinit/kinit.cpp:1361
#44 0x0000000000408b26 in main (argc=2, argv=0x7fff66b39558, envp=0x7fff66b39570) at /build/buildd/kde4libs-4.3.0/kinit/kinit.cpp:1788

Reported using DrKonqi