Application that crashed: plasma-desktop
Version of the application: 0.3
KDE Version: 4.3.2 (KDE 4.3.2)
Qt Version: 4.5.3
Operating System: Linux 2.6.31-ARCH x86_64

What I was doing when the application crashed:
I tried adding a fancy tasks panel to see what it looked like. The panel started spazing out, so I removed it. This took some time and plasma became sluggish. Trying to access the activity menu made it finally crash and come back.

 -- Backtrace:
Application: Plasma Workspace (kdeinit4), signal: Segmentation fault
[Current thread is 1 (Thread 0x7fa1489d0750 (LWP 3085))]

Thread 2 (Thread 0x7fa1269d6910 (LWP 3091)):
#0  0x00007fa1481b6dd9 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
#1  0x00007fa1484263ab in QWaitCondition::wait(QMutex*, unsigned long) () from /usr/lib/libQtCore.so.4
#2  0x00007fa14489165c in ?? () from /usr/lib/libQtNetwork.so.4
#3  0x00007fa1484252e5 in ?? () from /usr/lib/libQtCore.so.4
#4  0x00007fa1481b257a in start_thread () from /lib/libpthread.so.0
#5  0x00007fa145b6d14d in clone () from /lib/libc.so.6
#6  0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7fa1489d0750 (LWP 3085)):
[KCrash Handler]
#5  0x00007fa146821354 in QGraphicsItem::isWidget() const () from /usr/lib/libQtGui.so.4
#6  0x00007fa146823a89 in QGraphicsItem::isWindow() const () from /usr/lib/libQtGui.so.4
#7  0x00007fa1468571d9 in QGraphicsScene::event(QEvent*) () from /usr/lib/libQtGui.so.4
#8  0x00007fa1462a360c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#9  0x00007fa1462aa8de in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#10 0x00007fa146ed75a6 in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#11 0x00007fa14850a33c in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#12 0x00007fa146868986 in QGraphicsView::viewportEvent(QEvent*) () from /usr/lib/libQtGui.so.4
#13 0x00007fa148509687 in QCoreApplicationPrivate::sendThroughObjectEventFilters(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#14 0x00007fa1462a35dc in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#15 0x00007fa1462aa8de in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#16 0x00007fa146ed75a6 in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#17 0x00007fa14850a33c in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#18 0x00007fa1462f220b in QWidget::event(QEvent*) () from /usr/lib/libQtGui.so.4
#19 0x00007fa14664b2b6 in QFrame::event(QEvent*) () from /usr/lib/libQtGui.so.4
#20 0x00007fa1466d9fe9 in QAbstractScrollArea::event(QEvent*) () from /usr/lib/libQtGui.so.4
#21 0x00007fa1462a360c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#22 0x00007fa1462aa8de in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#23 0x00007fa146ed75a6 in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#24 0x00007fa14850a33c in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#25 0x00007fa1462adc6b in QApplication::setActiveWindow(QWidget*) () from /usr/lib/libQtGui.so.4
#26 0x00007fa14630f14e in QApplication::x11ProcessEvent(_XEvent*) () from /usr/lib/libQtGui.so.4
#27 0x00007fa146336efc in ?? () from /usr/lib/libQtGui.so.4
#28 0x00007fa1451f71fe in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#29 0x00007fa1451fabb8 in g_main_context_iterate () from /usr/lib/libglib-2.0.so.0
#30 0x00007fa1451face0 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#31 0x00007fa148532863 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#32 0x00007fa1463366de in ?? () from /usr/lib/libQtGui.so.4
#33 0x00007fa148508c72 in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#34 0x00007fa148509044 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#35 0x00007fa14850b1f9 in QCoreApplication::exec() () from /usr/lib/libQtCore.so.4
#36 0x00007fa13c64384f in kdemain (argc=<value optimized out>, argv=<value optimized out>) at /home/phil/kdemod/core/kdebase-workspace/src/kdebase-workspace-4.3.2/plasma/shells/desktop/main.cpp:50
#37 0x0000000000406eae in _start ()

Reported using DrKonqi