Application that crashed: plasma-desktop
Version of the application: 0.3
KDE Version: 4.3.3 (KDE 4.3.3)
Qt Version: 4.5.3
Operating System: Linux 2.6.31-ARCH x86_64

What I was doing when the application crashed:
I opened a *.pdf file by Okular. It created many grouped widgets in bar. When closed one, Plasma crashed

 -- Backtrace:
Application: Przestrzeń robocza Plazmy (kdeinit4), signal: Segmentation fault
[Current thread is 1 (Thread 0x7f0ef1061760 (LWP 1746))]

Thread 2 (Thread 0x7f0ed1f1c710 (LWP 1770)):
#0  0x00007f0ef084307c in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
#1  0x00007f0ef0aaec6b in QWaitCondition::wait(QMutex*, unsigned long) () from /usr/lib/libQtCore.so.4
#2  0x00007f0eecf29c9c in ?? () from /usr/lib/libQtNetwork.so.4
#3  0x00007f0ef0aadba5 in ?? () from /usr/lib/libQtCore.so.4
#4  0x00007f0ef083e81a in start_thread () from /lib/libpthread.so.0
#5  0x00007f0eee2078cd in clone () from /lib/libc.so.6
#6  0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7f0ef1061760 (LWP 1746)):
[KCrash Handler]
#5  0x00007f0ed3422b78 in AbstractTaskItem::basicPreferredSize() const () from /usr/lib/kde4/plasma_applet_tasks.so
#6  0x00007f0ed341e5d5 in TaskItemLayout::preferredColumns() () from /usr/lib/kde4/plasma_applet_tasks.so
#7  0x00007f0ed341f37d in TaskItemLayout::gridLayoutSize() () from /usr/lib/kde4/plasma_applet_tasks.so
#8  0x00007f0ed341f410 in TaskItemLayout::layoutItems() () from /usr/lib/kde4/plasma_applet_tasks.so
#9  0x00007f0ed341fcfb in TaskItemLayout::insert(int, AbstractTaskItem*) () from /usr/lib/kde4/plasma_applet_tasks.so
#10 0x00007f0ed341fef0 in TaskItemLayout::addTaskItem(AbstractTaskItem*) () from /usr/lib/kde4/plasma_applet_tasks.so
#11 0x00007f0ed342c0c8 in TaskGroupItem::itemAdded(TaskManager::AbstractGroupableItem*) () from /usr/lib/kde4/plasma_applet_tasks.so
#12 0x00007f0ed342c754 in TaskGroupItem::qt_metacall(QMetaObject::Call, int, void**) () from /usr/lib/kde4/plasma_applet_tasks.so
#13 0x00007f0ef0ba7d3c in QMetaObject::activate(QObject*, int, int, void**) () from /usr/lib/libQtCore.so.4
#14 0x00007f0ed3665eff in TaskManager::TaskGroup::itemAdded(TaskManager::AbstractGroupableItem*) () from /usr/lib/libtaskmanager.so.4
#15 0x00007f0ed36667ef in TaskManager::TaskGroup::add(TaskManager::AbstractGroupableItem*) () from /usr/lib/libtaskmanager.so.4
#16 0x00007f0ed364da15 in TaskManager::AbstractGroupingStrategy::closeGroup(TaskManager::TaskGroup*) () from /usr/lib/libtaskmanager.so.4
#17 0x00007f0ed3654b6f in TaskManager::ProgramGroupingStrategy::checkGroup() () from /usr/lib/libtaskmanager.so.4
#18 0x00007f0ed3655afc in TaskManager::ProgramGroupingStrategy::qt_metacall(QMetaObject::Call, int, void**) () from /usr/lib/libtaskmanager.so.4
#19 0x00007f0ef0ba7d3c in QMetaObject::activate(QObject*, int, int, void**) () from /usr/lib/libQtCore.so.4
#20 0x00007f0ed3665ec2 in TaskManager::TaskGroup::itemRemoved(TaskManager::AbstractGroupableItem*) () from /usr/lib/libtaskmanager.so.4
#21 0x00007f0ed36665a1 in TaskManager::TaskGroup::remove(TaskManager::AbstractGroupableItem*) () from /usr/lib/libtaskmanager.so.4
#22 0x00007f0ed36506ab in TaskManager::GroupManagerPrivate::removeTask(KSharedPtr<TaskManager::Task>) () from /usr/lib/libtaskmanager.so.4
#23 0x00007f0ed365237a in TaskManager::GroupManager::qt_metacall(QMetaObject::Call, int, void**) () from /usr/lib/libtaskmanager.so.4
#24 0x00007f0ef0ba7d3c in QMetaObject::activate(QObject*, int, int, void**) () from /usr/lib/libQtCore.so.4
#25 0x00007f0ed3669385 in TaskManager::TaskManager::taskRemoved(KSharedPtr<TaskManager::Task>) () from /usr/lib/libtaskmanager.so.4
#26 0x00007f0ed366af4d in TaskManager::TaskManager::windowRemoved(unsigned long) () from /usr/lib/libtaskmanager.so.4
#27 0x00007f0ed366c6e7 in TaskManager::TaskManager::qt_metacall(QMetaObject::Call, int, void**) () from /usr/lib/libtaskmanager.so.4
#28 0x00007f0ef0ba7d3c in QMetaObject::activate(QObject*, int, int, void**) () from /usr/lib/libQtCore.so.4
#29 0x00007f0eef68cd42 in KWindowSystem::windowRemoved(unsigned long) () from /usr/lib/libkdeui.so.5
#30 0x00007f0eef68fada in KWindowSystemPrivate::removeClient(unsigned long) () from /usr/lib/libkdeui.so.5
#31 0x00007f0eef69d51d in NETRootInfo::update(unsigned long const*) () from /usr/lib/libkdeui.so.5
#32 0x00007f0eef69e271 in NETRootInfo::event(_XEvent*, unsigned long*, int) () from /usr/lib/libkdeui.so.5
#33 0x00007f0eef68fd8c in KWindowSystemPrivate::x11Event(_XEvent*) () from /usr/lib/libkdeui.so.5
#34 0x00007f0eef560dc6 in KApplication::x11EventFilter(_XEvent*) () from /usr/lib/libkdeui.so.5
#35 0x00007f0ee4a6c624 in PlasmaApp::x11EventFilter(_XEvent*) () from /usr/lib/libkdeinit4_plasma-desktop.so
#36 0x00007f0eee988491 in ?? () from /usr/lib/libQtGui.so.4
#37 0x00007f0eee998a79 in QApplication::x11ProcessEvent(_XEvent*) () from /usr/lib/libQtGui.so.4
#38 0x00007f0eee9c196c in ?? () from /usr/lib/libQtGui.so.4
#39 0x00007f0eed88e1fe in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#40 0x00007f0eed891bb8 in g_main_context_iterate () from /usr/lib/libglib-2.0.so.0
#41 0x00007f0eed891ce0 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#42 0x00007f0ef0bbb123 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#43 0x00007f0eee9c114e in ?? () from /usr/lib/libQtGui.so.4
#44 0x00007f0ef0b91532 in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#45 0x00007f0ef0b91904 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#46 0x00007f0ef0b93ab9 in QCoreApplication::exec() () from /usr/lib/libQtCore.so.4
#47 0x00007f0ee4a5928f in kdemain () from /usr/lib/libkdeinit4_plasma-desktop.so
#48 0x0000000000406eae in _start ()

Reported using DrKonqi