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 have changed effect for window swithing from "flip switch" to "cover switch" and it changed but plasma crashed during this change. Reproducable.

 -- Backtrace:
Application: Plasma Workspace (kdeinit4), signal: Segmentation fault
[Current thread is 0 (LWP 3311)]

Thread 2 (Thread 0x7fd7b15bf950 (LWP 3374)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:261
#1  0x00007fd7d1421d19 in QWaitCondition::wait (this=0x144c500, mutex=0x144c4f8, time=18446744073709551615) at thread/qwaitcondition_unix.cpp:87
#2  0x00007fd7d02ab81c in QHostInfoAgent::run (this=0x144c4e0) at kernel/qhostinfo.cpp:260
#3  0x00007fd7d1420d35 in QThreadPrivate::start (arg=0x144c4e0) at thread/qthread_unix.cpp:188
#4  0x00007fd7cd31a3ba in start_thread (arg=<value optimized out>) at pthread_create.c:297
#5  0x00007fd7cdefefcd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#6  0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7fd7d19eb750 (LWP 3311)):
[KCrash Handler]
#5  0x00007fd7c8e74ccf in Plasma::FrameSvg::setElementPrefix (this=0x2f6ca10, prefix=@0x7fffd9a1c5d0) at /usr/include/qt4/QtCore/qstring.h:711
#6  0x00007fd7b3fddeeb in AbstractTaskItem::syncActiveRect (this=0x126e910) at /build/buildd/kdebase-workspace-4.3.0/plasma/applets/tasks/abstracttaskitem.cpp:503
#7  0x00007fd7b3fde0e0 in AbstractTaskItem::qt_metacall (this=0x126e910, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0x7fffd9a1c700)
    at /build/buildd/kdebase-workspace-4.3.0/obj-x86_64-linux-gnu/plasma/applets/tasks/abstracttaskitem.moc:90
#8  0x00007fd7b3fd55f5 in WindowTaskItem::qt_metacall (this=0x2f6ca10, _c=3651257808, _id=6, _a=0x2f8bb70)
    at /build/buildd/kdebase-workspace-4.3.0/obj-x86_64-linux-gnu/plasma/applets/tasks/windowtaskitem.moc:66
#9  0x00007fd7d151fea2 in QMetaObject::activate (sender=0xf42f60, from_signal_index=<value optimized out>, to_signal_index=4, argv=0x2f8bb70) at kernel/qobject.cpp:3113
#10 0x00007fd7c8eb16d1 in Plasma::Theme::qt_metacall (this=0xf42f60, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0x7fffd9a1c870)
    at /build/buildd/kde4libs-4.3.0/obj-x86_64-linux-gnu/plasma/theme.moc:102
#11 0x00007fd7d151fea2 in QMetaObject::activate (sender=0xf43b60, from_signal_index=<value optimized out>, to_signal_index=5, argv=0x2f8bb70) at kernel/qobject.cpp:3113
#12 0x00007fd7cfc53c5d in KSelectionWatcher::Private::x11Event (this=<value optimized out>, ev_P=0x7fffd9a1c5d0) at /build/buildd/kde4libs-4.3.0/kdeui/util/kmanagerselection.cpp:395
#13 0x00007fd7cfbe7b33 in KApplication::x11EventFilter (this=<value optimized out>, _event=0x7fffd9a1e270) at /build/buildd/kde4libs-4.3.0/kdeui/kernel/kapplication.cpp:911
#14 0x00007fd7c5461707 in PlasmaApp::x11EventFilter (this=0xe91ea0, event=0x7fffd9a1e270) at /build/buildd/kdebase-workspace-4.3.0/plasma/shells/desktop/plasmaapp.cpp:490
#15 0x00007fd7ceb3237f in qt_x11EventFilter (ev=0x7fffd9a1e270) at kernel/qapplication_x11.cpp:375
#16 0x00007fd7ceb4587e in QApplication::x11ProcessEvent (this=0xe91ea0, event=0x7fffd9a1e270) at kernel/qapplication_x11.cpp:3271
#17 0x00007fd7ceb6f454 in x11EventSourceDispatch (s=0xed4320, callback=0, user_data=0x0) at kernel/qguieventdispatcher_glib.cpp:146
#18 0x00007fd7cd56920a in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#19 0x00007fd7cd56c8e0 in ?? () from /usr/lib/libglib-2.0.so.0
#20 0x00007fd7cd56ca7c in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#21 0x00007fd7d1533a8f in QEventDispatcherGlib::processEvents (this=0xed0840, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:327
#22 0x00007fd7ceb6ebdf in QGuiEventDispatcherGlib::processEvents (this=0x2f6ca10, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:202
#23 0x00007fd7d1508f42 in QEventLoop::processEvents (this=<value optimized out>, flags={i = -643701408}) at kernel/qeventloop.cpp:149
#24 0x00007fd7d1509314 in QEventLoop::exec (this=0x7fffd9a1e5a0, flags={i = -643701328}) at kernel/qeventloop.cpp:201
#25 0x00007fd7d150b5e4 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#26 0x00007fd7c544e1eb in kdemain (argc=1, argv=0xe5aa50) at /build/buildd/kdebase-workspace-4.3.0/plasma/shells/desktop/main.cpp:50
#27 0x0000000000407215 in launch (argc=1, _name=0xe85468 "/usr/bin/plasma-desktop", args=<value optimized out>, cwd=0x0, envc=0, envs=0xe85488 "", reset_env=false, tty=0x0, avoid_loops=false, 
    startup_id_str=0x40a3a1 "0") at /build/buildd/kde4libs-4.3.0/kinit/kinit.cpp:676
#28 0x0000000000407a38 in handle_launcher_request (sock=7, who=<value optimized out>) at /build/buildd/kde4libs-4.3.0/kinit/kinit.cpp:1168
#29 0x0000000000407fe5 in handle_requests (waitForPid=0) at /build/buildd/kde4libs-4.3.0/kinit/kinit.cpp:1361
#30 0x0000000000408b26 in main (argc=2, argv=0x7fffd9a1f448, envp=0x7fffd9a1f460) at /build/buildd/kde4libs-4.3.0/kinit/kinit.cpp:1788

Reported using DrKonqi