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 i686
Distribution: Ubuntu 9.10

What I was doing when the application crashed:
But it restarted right after.

Just a few applications were running, like FFox, a konsole and Ark. 

 -- Backtrace:
Application: Plasma Workspace (kdeinit4), signal: Segmentation fault
[KCrash Handler]
#6  0x0567418a in QGraphicsItem::isWidget() const () from /usr/lib/libQtGui.so.4
#7  0x056ad527 in QGraphicsScene::event(QEvent*) () from /usr/lib/libQtGui.so.4
#8  0x05070f54 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#9  0x0507867c in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#10 0x00f5ebfa in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#11 0x0035f6cb in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#12 0x056be5e7 in QGraphicsView::viewportEvent(QEvent*) () from /usr/lib/libQtGui.so.4
#13 0x05516a95 in ?? () from /usr/lib/libQtGui.so.4
#14 0x0035e83a in QCoreApplicationPrivate::sendThroughObjectEventFilters(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#15 0x05070f2c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#16 0x050785ca in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#17 0x00f5ebfa in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#18 0x0035f6cb in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#19 0x050c5ad5 in QWidget::event(QEvent*) () from /usr/lib/libQtGui.so.4
#20 0x05475633 in QFrame::event(QEvent*) () from /usr/lib/libQtGui.so.4
#21 0x05514faa in QAbstractScrollArea::event(QEvent*) () from /usr/lib/libQtGui.so.4
#22 0x056be406 in QGraphicsView::event(QEvent*) () from /usr/lib/libQtGui.so.4
#23 0x05070f54 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#24 0x050785ca in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#25 0x00f5ebfa in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#26 0x0035f6cb in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#27 0x0507bdf6 in QApplication::setActiveWindow(QWidget*) () from /usr/lib/libQtGui.so.4
#28 0x050e521f in QApplication::x11ProcessEvent(_XEvent*) () from /usr/lib/libQtGui.so.4
#29 0x05112502 in ?? () from /usr/lib/libQtGui.so.4
#30 0x005bae88 in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#31 0x005be730 in ?? () from /lib/libglib-2.0.so.0
#32 0x005be863 in g_main_context_iteration () from /lib/libglib-2.0.so.0
#33 0x0038a02c in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#34 0x05111be5 in ?? () from /usr/lib/libQtGui.so.4
#35 0x0035dc79 in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#36 0x0035e0ca in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#37 0x0036053f in QCoreApplication::exec() () from /usr/lib/libQtCore.so.4
#38 0x05070dd7 in QApplication::exec() () from /usr/lib/libQtGui.so.4
#39 0x08f2b80d in kdemain () from /usr/lib/libkdeinit4_plasma-desktop.so
#40 0x0804dde1 in _start ()

Reported using DrKonqi