Application that crashed: plasma-desktop
Version of the application: 0.3
KDE Version: 4.3.1 (KDE 4.3.1) "release 6"
Qt Version: 4.5.3
Operating System: Linux 2.6.31.5-0.1-desktop x86_64
Distribution: "openSUSE 11.2 (x86_64)"

What I was doing when the application crashed:
I opened the task manager settings to configure the behaviour of the taskbar. When I finished I clicked on the OK button and the task manager forced changed its configuration to 2 rows (I did not set that configuration). Next, when I wanted to see what was going on, I tried to open task manager settings and in that moment plasma crashed.

The settings set in task manager were:
show tooltips, maximum row: 2, grouping by program name only when taskbar is full and alphabetically sorted, filters: only show tasks from the current desktop.

KDE: Version 4.3.1 (KDE 4.3.1) "release 6" 
Opensuse 11.2

 -- Backtrace:
Application: Plasma Workspace (kdeinit4), signal: Segmentation fault
[Current thread is 1 (Thread 0x7f5c5ac89750 (LWP 2231))]

Thread 2 (Thread 0x7f5c3d496910 (LWP 2236)):
#0  0x00007f5c5a459049 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x00007f5c5a6c953b in QWaitCondition::wait(QMutex*, unsigned long) () from /usr/lib64/libQtCore.so.4
#2  0x00007f5c56ba29ec in ?? () from /usr/lib64/libQtNetwork.so.4
#3  0x00007f5c5a6c8485 in ?? () from /usr/lib64/libQtCore.so.4
#4  0x00007f5c5a45465d in start_thread () from /lib64/libpthread.so.0
#5  0x00007f5c57e6814d in clone () from /lib64/libc.so.6
#6  0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7f5c5ac89750 (LWP 2231)):
[KCrash Handler]
#5  itemTopMargin (this=<value optimized out>) at /usr/src/debug/kdebase-workspace-4.3.1/plasma/applets/tasks/tasks.h:92
#6  AbstractTaskItem::basicPreferredSize (this=<value optimized out>) at /usr/src/debug/kdebase-workspace-4.3.1/plasma/applets/tasks/abstracttaskitem.cpp:99
#7  0x00007f5c3eff42c5 in TaskItemLayout::preferredColumns (this=0xcf27e0) at /usr/src/debug/kdebase-workspace-4.3.1/plasma/applets/tasks/taskitemlayout.cpp:206
#8  0x00007f5c3eff4fad in TaskItemLayout::gridLayoutSize (this=0xcf27e0) at /usr/src/debug/kdebase-workspace-4.3.1/plasma/applets/tasks/taskitemlayout.cpp:222
#9  0x00007f5c3eff503b in TaskItemLayout::layoutItems (this=0x0) at /usr/src/debug/kdebase-workspace-4.3.1/plasma/applets/tasks/taskitemlayout.cpp:245
#10 0x00007f5c3eff5abf in TaskItemLayout::insert (this=0xcf27e0, index=<value optimized out>, item=0x1248b40) at /usr/src/debug/kdebase-workspace-4.3.1/plasma/applets/tasks/taskitemlayout.cpp:125
#11 0x00007f5c3eff5c90 in TaskItemLayout::addTaskItem (this=0xcf27e0, item=0x1248b40) at /usr/src/debug/kdebase-workspace-4.3.1/plasma/applets/tasks/taskitemlayout.cpp:82
#12 0x00007f5c3f0019c8 in TaskGroupItem::itemAdded (this=0xc95f70, groupableItem=0x19e99b0) at /usr/src/debug/kdebase-workspace-4.3.1/plasma/applets/tasks/taskgroupitem.cpp:477
#13 0x00007f5c3f002024 in TaskGroupItem::qt_metacall (this=0xc95f70, _c=InvokeMetaMethod, _id=<value optimized out>, _a=0x7fff026da660)
    at /usr/src/debug/kdebase-workspace-4.3.1/build/plasma/applets/tasks/taskgroupitem.moc:113
#14 0x00007f5c5a7c2fbc in QMetaObject::activate(QObject*, int, int, void**) () from /usr/lib64/libQtCore.so.4
#15 0x00007f5c3fcb638f in TaskManager::TaskGroup::itemAdded (this=0x0, _t1=0x19e99b0) at /usr/src/debug/kdebase-workspace-4.3.1/build/libs/taskmanager/taskgroup.moc:145
#16 0x00007f5c3fcb6c7f in TaskManager::TaskGroup::add (this=0xcc1870, item=0x19e99b0) at /usr/src/debug/kdebase-workspace-4.3.1/libs/taskmanager/taskgroup.cpp:138
#17 0x00007f5c3fca62dd in TaskManager::ProgramGroupingStrategy::handleItem (this=0x12ccb60, item=0x19e99b0)
    at /usr/src/debug/kdebase-workspace-4.3.1/libs/taskmanager/strategies/programgroupingstrategy.cpp:158
#18 0x00007f5c3fca051a in TaskManager::GroupManagerPrivate::addTask (this=0xc845a0, task=) at /usr/src/debug/kdebase-workspace-4.3.1/libs/taskmanager/groupmanager.cpp:288
#19 0x00007f5c3fca265a in TaskManager::GroupManager::qt_metacall (this=0xc8cc00, _c=<value optimized out>, _id=<value optimized out>, _a=0x7fff026da900)
    at /usr/src/debug/kdebase-workspace-4.3.1/build/libs/taskmanager/groupmanager.moc:103
#20 0x00007f5c5a7c2fbc in QMetaObject::activate(QObject*, int, int, void**) () from /usr/lib64/libQtCore.so.4
#21 0x00007f5c3fcb9842 in TaskManager::TaskManager::taskAdded (this=0x0, _t1=<value optimized out>) at /usr/src/debug/kdebase-workspace-4.3.1/build/libs/taskmanager/taskmanager.moc:155
#22 0x00007f5c3fcbb840 in TaskManager::TaskManager::windowAdded (this=0xc9f960, w=28318991) at /usr/src/debug/kdebase-workspace-4.3.1/libs/taskmanager/taskmanager.cpp:261
#23 0x00007f5c3fcbcb5f in TaskManager::TaskManager::qt_metacall (this=0xc9f960, _c=InvokeMetaMethod, _id=<value optimized out>, _a=0x7fff026daba0)
    at /usr/src/debug/kdebase-workspace-4.3.1/build/libs/taskmanager/taskmanager.moc:109
#24 0x00007f5c5a7c2fbc in QMetaObject::activate(QObject*, int, int, void**) () from /usr/lib64/libQtCore.so.4
#25 0x00007f5c592c4042 in KWindowSystem::windowAdded(unsigned long) () from /usr/lib64/libkdeui.so.5
#26 0x00007f5c592c6c6a in ?? () from /usr/lib64/libkdeui.so.5
#27 0x00007f5c592d49cd in NETRootInfo::update(unsigned long const*) () from /usr/lib64/libkdeui.so.5
#28 0x00007f5c592d56b3 in NETRootInfo::event(_XEvent*, unsigned long*, int) () from /usr/lib64/libkdeui.so.5
#29 0x00007f5c592c70bc in ?? () from /usr/lib64/libkdeui.so.5
#30 0x00007f5c59197d76 in KApplication::x11EventFilter(_XEvent*) () from /usr/lib64/libkdeui.so.5
#31 0x00007f5c4fc23437 in PlasmaApp::x11EventFilter (this=0x6702a0, event=0x7fff026dc8b0) at /usr/src/debug/kdebase-workspace-4.3.1/plasma/shells/desktop/plasmaapp.cpp:490
#32 0x00007f5c585f8681 in ?? () from /usr/lib64/libQtGui.so.4
#33 0x00007f5c58608d11 in QApplication::x11ProcessEvent(_XEvent*) () from /usr/lib64/libQtGui.so.4
#34 0x00007f5c58631b6c in ?? () from /usr/lib64/libQtGui.so.4
#35 0x00007f5c574e7dde in g_main_context_dispatch () from /usr/lib64/libglib-2.0.so.0
#36 0x00007f5c574eb7a8 in ?? () from /usr/lib64/libglib-2.0.so.0
#37 0x00007f5c574eb8d0 in g_main_context_iteration () from /usr/lib64/libglib-2.0.so.0
#38 0x00007f5c5a7d63a3 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib64/libQtCore.so.4
#39 0x00007f5c5863131e in ?? () from /usr/lib64/libQtGui.so.4
#40 0x00007f5c5a7ac712 in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib64/libQtCore.so.4
#41 0x00007f5c5a7acae4 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib64/libQtCore.so.4
#42 0x00007f5c5a7aec99 in QCoreApplication::exec() () from /usr/lib64/libQtCore.so.4
#43 0x00007f5c4fc0fd6f in kdemain (argc=<value optimized out>, argv=<value optimized out>) at /usr/src/debug/kdebase-workspace-4.3.1/plasma/shells/desktop/main.cpp:50
#44 0x0000000000406f88 in _start ()

Reported using DrKonqi