Application that crashed: plasma-desktop
Version of the application: 0.3
KDE Version: 4.3.2 (KDE 4.3.2)
Qt Version: 4.5.2
Operating System: Linux 2.6.31-16-generic x86_64
Distribution: Ubuntu 9.10

What I was doing when the application crashed:
Having 2 Firefox windows in one group on the taskbar, I clicked on the group and Plasma crashed, then automatically restarted.

 -- Backtrace:
Application: Plasma Workspace (kdeinit4), signal: Segmentation fault
[Current thread is 1 (Thread 0x7f31842c7750 (LWP 1766))]

Thread 2 (Thread 0x7f315a9d2910 (LWP 2924)):
#0  0x00007f3180a805a9 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
#1  0x00007f3183d064fb in QWaitCondition::wait(QMutex*, unsigned long) () from /usr/lib/libQtCore.so.4
#2  0x00007f318013d78c in ?? () from /usr/lib/libQtNetwork.so.4
#3  0x00007f3183d05445 in ?? () from /usr/lib/libQtCore.so.4
#4  0x00007f3180a7ba04 in start_thread () from /lib/libpthread.so.0
#5  0x00007f318165b7bd in clone () from /lib/libc.so.6
#6  0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7f31842c7750 (LWP 1766)):
[KCrash Handler]
#5  0x00007f318231c484 in QGraphicsItem::isWidget() const () from /usr/lib/libQtGui.so.4
#6  0x00007f318231eb89 in QGraphicsItem::isWindow() const () from /usr/lib/libQtGui.so.4
#7  0x00007f3182352269 in QGraphicsScene::event(QEvent*) () from /usr/lib/libQtGui.so.4
#8  0x00007f3181d9befc in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#9  0x00007f3181da31ce in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#10 0x00007f31829d2ab6 in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#11 0x00007f3183debc2c in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#12 0x00007f31823639f6 in QGraphicsView::viewportEvent(QEvent*) () from /usr/lib/libQtGui.so.4
#13 0x00007f3183deaf47 in QCoreApplicationPrivate::sendThroughObjectEventFilters(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#14 0x00007f3181d9becc in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#15 0x00007f3181da31ce in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#16 0x00007f31829d2ab6 in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#17 0x00007f3183debc2c in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#18 0x00007f3181deab6b in QWidget::event(QEvent*) () from /usr/lib/libQtGui.so.4
#19 0x00007f31821462a6 in QFrame::event(QEvent*) () from /usr/lib/libQtGui.so.4
#20 0x00007f31821d5bc9 in QAbstractScrollArea::event(QEvent*) () from /usr/lib/libQtGui.so.4
#21 0x00007f3181d9befc in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#22 0x00007f3181da31ce in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#23 0x00007f31829d2ab6 in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#24 0x00007f3183debc2c in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#25 0x00007f3181deab6b in QWidget::event(QEvent*) () from /usr/lib/libQtGui.so.4
#26 0x00007f317b917710 in Plasma::Dialog::event(QEvent*) () from /usr/lib/libplasma.so.3
#27 0x00007f3181d9befc in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#28 0x00007f3181da31ce in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#29 0x00007f31829d2ab6 in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#30 0x00007f3183debc2c in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#31 0x00007f3181da655b in QApplication::setActiveWindow(QWidget*) () from /usr/lib/libQtGui.so.4
#32 0x00007f3181e07b9e in QApplication::x11ProcessEvent(_XEvent*) () from /usr/lib/libQtGui.so.4
#33 0x00007f3181e30d0c in ?? () from /usr/lib/libQtGui.so.4
#34 0x00007f3180cccbbe in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#35 0x00007f3180cd0588 in ?? () from /lib/libglib-2.0.so.0
#36 0x00007f3180cd06b0 in g_main_context_iteration () from /lib/libglib-2.0.so.0
#37 0x00007f3183e141a6 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#38 0x00007f3181e304be in ?? () from /usr/lib/libQtGui.so.4
#39 0x00007f3183dea532 in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#40 0x00007f3183dea904 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#41 0x00007f3183decab9 in QCoreApplication::exec() () from /usr/lib/libQtCore.so.4
#42 0x00007f317816d4cf in kdemain () from /usr/lib/libkdeinit4_plasma-desktop.so
#43 0x0000000000406da8 in _start ()

Reported using DrKonqi