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 2.6.30-gentoo-r1 x86_64

What I was doing when the application crashed:
started Konqueror and it crash plasma-workspace
i have already have this when launching firefox. 
I have 2 planels on my screen, 

When i click restart the application it works !

 -- Backtrace:
Application: Plasma Workspace (kdeinit4), signal: Segmentation fault
[Current thread is 0 (LWP 14657)]

Thread 2 (Thread 0x7fe6dcbaa910 (LWP 14662)):
#0  0x00007fe6fcee8279 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
#1  0x00007fe6fd1579c5 in QWaitCondition::wait (this=0xe53cf0, mutex=0xe53ce8, time=18446744073709551615) at thread/qwaitcondition_unix.cpp:87
#2  0x00007fe6fbdd7914 in QHostInfoAgent::run (this=0xe53cd0) at kernel/qhostinfo.cpp:260
#3  0x00007fe6fd156e04 in QThreadPrivate::start (arg=0xe53cd0) at thread/qthread_unix.cpp:188
#4  0x00007fe6fcee42e7 in start_thread () from /lib/libpthread.so.0
#5  0x00007fe6f9ae538d in clone () from /lib/libc.so.6
#6  0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7fe6fd6e4740 (LWP 14657)):
[KCrash Handler]
#5  Tasks::itemTopMargin (this=0x2) at /var/tmp/portage/kde-base/plasma-workspace-4.3.1/work/plasma-workspace-4.3.1/plasma/applets/tasks/tasks.h:92
#6  0x00007fe6e105de73 in AbstractTaskItem::basicPreferredSize (this=0x12734c0)
    at /var/tmp/portage/kde-base/plasma-workspace-4.3.1/work/plasma-workspace-4.3.1/plasma/applets/tasks/abstracttaskitem.cpp:99
#7  0x00007fe6e1057ab5 in TaskItemLayout::maximumRows (this=0xc66840) at /var/tmp/portage/kde-base/plasma-workspace-4.3.1/work/plasma-workspace-4.3.1/plasma/applets/tasks/taskitemlayout.cpp:185
#8  0x00007fe6e1060497 in TaskGroupItem::optimumCapacity (this=0xc693b0) at /var/tmp/portage/kde-base/plasma-workspace-4.3.1/work/plasma-workspace-4.3.1/plasma/applets/tasks/taskgroupitem.cpp:1224
#9  0x00007fe6e1054051 in Tasks::adjustGroupingStrategy (this=0xad13b0) at /var/tmp/portage/kde-base/plasma-workspace-4.3.1/work/plasma-workspace-4.3.1/plasma/applets/tasks/tasks.cpp:241
#10 0x00007fe6e1054a8f in Tasks::constraintsEvent (this=0xad13b0, constraints={i = -1301076240})
    at /var/tmp/portage/kde-base/plasma-workspace-4.3.1/work/plasma-workspace-4.3.1/plasma/applets/tasks/tasks.cpp:165
#11 0x00007fe6f45b15fc in Plasma::Applet::flushPendingConstraintsEvents (this=0xad13b0) at /var/tmp/portage/kde-base/kdelibs-4.3.1/work/kdelibs-4.3.1/plasma/applet.cpp:1163
#12 0x00007fe6f45b1c02 in Plasma::Applet::timerEvent (this=0xad13b0, event=<value optimized out>) at /var/tmp/portage/kde-base/kdelibs-4.3.1/work/kdelibs-4.3.1/plasma/applet.cpp:2110
#13 0x00007fe6fd248073 in QObject::event (this=0xad13b0, e=0x7fe6f9b35ef8) at kernel/qobject.cpp:1066
#14 0x00007fe6fac5235b in QGraphicsWidget::event (this=0xad13b0, event=0x7fffb2732f70) at graphicsview/qgraphicswidget.cpp:1340
#15 0x00007fe6fa6b203d in QApplicationPrivate::notify_helper (this=0x66e340, receiver=0xad13b0, e=0x7fffb2732f70) at kernel/qapplication.cpp:4056
#16 0x00007fe6fa6bac9e in QApplication::notify (this=0x6651f0, receiver=0xad13b0, e=0x7fffb2732f70) at kernel/qapplication.cpp:4021
#17 0x00007fe6fb6f9601 in KApplication::notify (this=0x6651f0, receiver=0xad13b0, event=0x7fffb2732f70) at /var/tmp/portage/kde-base/kdelibs-4.3.1/work/kdelibs-4.3.1/kdeui/kernel/kapplication.cpp:302
#18 0x00007fe6fd2380fb in QCoreApplication::notifyInternal (this=0x6651f0, receiver=0xad13b0, event=0x7fffb2732f70) at kernel/qcoreapplication.cpp:606
#19 0x00007fe6fd262e56 in QTimerInfoList::activateTimers (this=0x6717c0) at kernel/qcoreapplication.h:213
#20 0x00007fe6fd26014d in timerSourceDispatch (source=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:165
#21 0x00007fe6f913ad9d in g_main_dispatch () from /usr/lib/libglib-2.0.so.0
#22 0x00007fe6f913cb2d in g_main_context_iterate () from /usr/lib/libglib-2.0.so.0
#23 0x00007fe6f913cc8c in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#24 0x00007fe6fd2600af in QEventDispatcherGlib::processEvents (this=0x66e0c0, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:327
#25 0x00007fe6fa7411ef in QGuiEventDispatcherGlib::processEvents (this=0x2, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:202
#26 0x00007fe6fd236d42 in QEventLoop::processEvents (this=<value optimized out>, flags={i = -1301073440}) at kernel/qeventloop.cpp:149
#27 0x00007fe6fd236edc in QEventLoop::exec (this=0x7fffb2733220, flags={i = -1301073360}) at kernel/qeventloop.cpp:197
#28 0x00007fe6fd23ba3e in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#29 0x00007fe6f0dc0cdb in kdemain (argc=1, argv=0x649910) at /var/tmp/portage/kde-base/plasma-workspace-4.3.1/work/plasma-workspace-4.3.1/plasma/shells/desktop/main.cpp:50
#30 0x000000000040735b in launch (argc=1, _name=0x650b58 "/usr/bin/plasma-desktop", args=0x650b70 "", cwd=0x0, envc=0, envs=<value optimized out>, reset_env=false, tty=0x0, avoid_loops=false, 
    startup_id_str=0x40b1b4 "0") at /var/tmp/portage/kde-base/kdelibs-4.3.1/work/kdelibs-4.3.1/kinit/kinit.cpp:677
#31 0x0000000000407e72 in handle_launcher_request (sock=8, who=<value optimized out>) at /var/tmp/portage/kde-base/kdelibs-4.3.1/work/kdelibs-4.3.1/kinit/kinit.cpp:1169
#32 0x0000000000408571 in handle_requests (waitForPid=0) at /var/tmp/portage/kde-base/kdelibs-4.3.1/work/kdelibs-4.3.1/kinit/kinit.cpp:1362
#33 0x0000000000408acd in main (argc=2, argv=0x7fffb2733e98, envp=0x7fffb2733eb0) at /var/tmp/portage/kde-base/kdelibs-4.3.1/work/kdelibs-4.3.1/kinit/kinit.cpp:1793

This bug may be a duplicate of or related to bug 208399

Reported using DrKonqi