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 2.6.31-20-generic i686
Distribution: Ubuntu 9.10

What I was doing when the application crashed:
I (accidentally) used the mouse wheel on a visible part of the desktop, which caused the screen to go blank for while, before the Plasma Workspace crash report appeared.

 -- Backtrace:
Application: Plasma Workspace (kdeinit4), signal: Segmentation fault
[Current thread is 1 (Thread 0xb7795700 (LWP 1808))]

Thread 2 (Thread 0xac6bab70 (LWP 1809)):
#0  0x00bc1422 in __kernel_vsyscall ()
#1  0x00800e15 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/tls/i686/cmov/libpthread.so.0
#2  0x00ae787d in pthread_cond_wait () from /lib/tls/i686/cmov/libc.so.6
#3  0x00c15e67 in QWaitCondition::wait(QMutex*, unsigned long) () from /usr/lib/libQtCore.so.4
#4  0x0612b922 in ?? () from /usr/lib/libQtNetwork.so.4
#5  0x00c14e32 in ?? () from /usr/lib/libQtCore.so.4
#6  0x007fc80e in start_thread () from /lib/tls/i686/cmov/libpthread.so.0
#7  0x00ada8de in clone () from /lib/tls/i686/cmov/libc.so.6

Thread 1 (Thread 0xb7795700 (LWP 1808)):
[KCrash Handler]
#6  0x018af18a in QGraphicsItem::isWidget() const () from /usr/lib/libQtGui.so.4
#7  0x018e8527 in QGraphicsScene::event(QEvent*) () from /usr/lib/libQtGui.so.4
#8  0x012abf54 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#9  0x012b367c in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#10 0x00fcbbfa in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#11 0x00d056cb in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#12 0x018f95e7 in QGraphicsView::viewportEvent(QEvent*) () from /usr/lib/libQtGui.so.4
#13 0x01751a95 in ?? () from /usr/lib/libQtGui.so.4
#14 0x00d0483a in QCoreApplicationPrivate::sendThroughObjectEventFilters(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#15 0x012abf2c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#16 0x012b35ca in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#17 0x00fcbbfa in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#18 0x00d056cb in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#19 0x01300ad5 in QWidget::event(QEvent*) () from /usr/lib/libQtGui.so.4
#20 0x016b0633 in QFrame::event(QEvent*) () from /usr/lib/libQtGui.so.4
#21 0x0174ffaa in QAbstractScrollArea::event(QEvent*) () from /usr/lib/libQtGui.so.4
#22 0x018f9406 in QGraphicsView::event(QEvent*) () from /usr/lib/libQtGui.so.4
#23 0x012abf54 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#24 0x012b35ca in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#25 0x00fcbbfa in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#26 0x00d056cb in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#27 0x012b6df6 in QApplication::setActiveWindow(QWidget*) () from /usr/lib/libQtGui.so.4
#28 0x0132021f in QApplication::x11ProcessEvent(_XEvent*) () from /usr/lib/libQtGui.so.4
#29 0x0134d502 in ?? () from /usr/lib/libQtGui.so.4
#30 0x004a8e88 in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#31 0x004ac730 in ?? () from /lib/libglib-2.0.so.0
#32 0x004ac863 in g_main_context_iteration () from /lib/libglib-2.0.so.0
#33 0x00d3002c in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#34 0x0134cbe5 in ?? () from /usr/lib/libQtGui.so.4
#35 0x00d03c79 in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#36 0x00d040ca in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#37 0x00d0653f in QCoreApplication::exec() () from /usr/lib/libQtCore.so.4
#38 0x012abdd7 in QApplication::exec() () from /usr/lib/libQtGui.so.4
#39 0x0771380d in kdemain () from /usr/lib/libkdeinit4_plasma-desktop.so
#40 0x0804dde1 in _start ()

Reported using DrKonqi