Application that crashed: plasma-desktop
Version of the application: 0.3
KDE Version: 4.3.1 (KDE 4.3.1)
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:
Woking ok till I started Epiphany browser. KDE 4.3.1 crashed. Similar problem experienced when using Xpn (newseader) too, except the whole screen went black, with just the cursor arrow showing.

 -- Backtrace:
Application: Plasma Workspace (kdeinit4), signal: Segmentation fault
[Current thread is 0 (LWP 20136)]

Thread 2 (Thread 0x7fdb2027f950 (LWP 20137)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:261
#1  0x00007fdb406a4d19 in QWaitCondition::wait (this=0x1462240, mutex=0x1462238, time=18446744073709551615) at thread/qwaitcondition_unix.cpp:87
#2  0x00007fdb3f52a81c in QHostInfoAgent::run (this=0x1462220) at kernel/qhostinfo.cpp:260
#3  0x00007fdb406a3d35 in QThreadPrivate::start (arg=0x1462220) at thread/qthread_unix.cpp:188
#4  0x00007fdb3c5983ba in start_thread (arg=<value optimized out>) at pthread_create.c:297
#5  0x00007fdb3d17cfcd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#6  0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7fdb40c6f750 (LWP 20136)):
[KCrash Handler]
#5  0x00007fdb3e341734 in QGraphicsLayoutItem::geometry (this=0x140d420) at graphicsview/qgraphicslayoutitem.cpp:664
#6  0x00007fdb3e345145 in QGraphicsWidget::size (this=<value optimized out>) at graphicsview/qgraphicswidget.cpp:336
#7  0x00007fdb21424e7e in AbstractTaskItem::basicPreferredSize (this=0x27d4970) at /build/buildd/kdebase-workspace-4.3.1/plasma/applets/tasks/abstracttaskitem.cpp:108
#8  0x00007fdb214214c2 in TaskItemLayout::maximumRows (this=0x15fc6d0) at /build/buildd/kdebase-workspace-4.3.1/plasma/applets/tasks/taskitemlayout.cpp:185
#9  0x00007fdb21429b37 in TaskGroupItem::optimumCapacity (this=0x160c710) at /build/buildd/kdebase-workspace-4.3.1/plasma/applets/tasks/taskgroupitem.cpp:1224
#10 0x00007fdb2141cdf0 in Tasks::adjustGroupingStrategy (this=0xfeb170) at /build/buildd/kdebase-workspace-4.3.1/plasma/applets/tasks/tasks.cpp:241
#11 0x00007fdb2141d008 in Tasks::constraintsEvent (this=0xfeb170, constraints={i = 21025824}) at /build/buildd/kdebase-workspace-4.3.1/plasma/applets/tasks/tasks.cpp:165
#12 0x00007fdb380ade69 in Plasma::Applet::flushPendingConstraintsEvents (this=0xfeb170) at /build/buildd/kde4libs-4.3.1/plasma/applet.cpp:1173
#13 0x00007fdb380ae4b5 in Plasma::Applet::timerEvent (this=0xfeb170, event=<value optimized out>) at /build/buildd/kde4libs-4.3.1/plasma/applet.cpp:2120
#14 0x00007fdb4079d263 in QObject::event (this=0xfeb170, e=0x140d420) at kernel/qobject.cpp:1075
#15 0x00007fdb3e34618b in QGraphicsWidget::event (this=0xfeb170, event=0x7fff48c9f580) at graphicsview/qgraphicswidget.cpp:1340
#16 0x00007fdb3dd53f4d in QApplicationPrivate::notify_helper (this=0xb641e0, receiver=0xfeb170, e=0x7fff48c9f580) at kernel/qapplication.cpp:4056
#17 0x00007fdb3dd5c18a in QApplication::notify (this=0xb25370, receiver=0xfeb170, e=0x7fff48c9f580) at kernel/qapplication.cpp:4021
#18 0x00007fdb3ee66deb in KApplication::notify (this=0xb25370, receiver=0xfeb170, event=0x7fff48c9f580) at /build/buildd/kde4libs-4.3.1/kdeui/kernel/kapplication.cpp:302
#19 0x00007fdb4078d6ac in QCoreApplication::notifyInternal (this=0xb25370, receiver=0xfeb170, event=0x7fff48c9f580) at kernel/qcoreapplication.cpp:610
#20 0x00007fdb407ba516 in QTimerInfoList::activateTimers (this=0xb677a0) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:213
#21 0x00007fdb407b6b2d in timerSourceDispatch (source=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:165
#22 0x00007fdb3c7e720a in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#23 0x00007fdb3c7ea8e0 in ?? () from /usr/lib/libglib-2.0.so.0
#24 0x00007fdb3c7eaa7c in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#25 0x00007fdb407b6a8f in QEventDispatcherGlib::processEvents (this=0xb63d10, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:327
#26 0x00007fdb3ddecbdf in QGuiEventDispatcherGlib::processEvents (this=0x7fff48c9eb40, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:202
#27 0x00007fdb4078bf42 in QEventLoop::processEvents (this=<value optimized out>, flags={i = 1221195760}) at kernel/qeventloop.cpp:149
#28 0x00007fdb4078c314 in QEventLoop::exec (this=0x7fff48c9f830, flags={i = 1221195840}) at kernel/qeventloop.cpp:201
#29 0x00007fdb4078e5e4 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#30 0x00007fdb346cd3eb in kdemain (argc=1, argv=0xad19b0) at /build/buildd/kdebase-workspace-4.3.1/plasma/shells/desktop/main.cpp:50
#31 0x0000000000407215 in launch (argc=1, _name=0xb18448 "/usr/bin/plasma-desktop", args=<value optimized out>, cwd=0x0, envc=0, envs=0xb18468 "", reset_env=false, tty=0x0, avoid_loops=false, 
    startup_id_str=0x40a3a1 "0") at /build/buildd/kde4libs-4.3.1/kinit/kinit.cpp:677
#32 0x0000000000407a38 in handle_launcher_request (sock=7, who=<value optimized out>) at /build/buildd/kde4libs-4.3.1/kinit/kinit.cpp:1169
#33 0x0000000000407fe5 in handle_requests (waitForPid=0) at /build/buildd/kde4libs-4.3.1/kinit/kinit.cpp:1362
#34 0x0000000000408b26 in main (argc=2, argv=0x7fff48ca06d8, envp=0x7fff48ca06f0) at /build/buildd/kde4libs-4.3.1/kinit/kinit.cpp:1793

Reported using DrKonqi