Application that crashed: plasma-desktop
Version of the application: 0.3
KDE Version: 4.3.4 (KDE 4.3.4)
Qt Version: 4.5.3
Operating System: Linux 2.6.31.5-server-1mnb i686
Distribution: "Mandriva Linux 2010.0"

What I was doing when the application crashed:
only I have working with firefox 3.5 and Kmess and plasma crashes, its the first time to this occur 

 -- Backtrace:
Application: Área de trabajo de Plasma (kdeinit4), signal: Segmentation fault
[Current thread is 1 (Thread 0xb57ce6d0 (LWP 4470))]

Thread 2 (Thread 0xa6e2cb70 (LWP 4540)):
#0  0xffffe424 in __kernel_vsyscall ()
#1  0xb765e9e5 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/i686/libpthread.so.0
#2  0xb76b9fb0 in QWaitCondition::wait () from /usr/lib/libQtCore.so.4
#3  0xb6f25194 in ?? () from /usr/lib/libQtNetwork.so.4
#4  0xb76b8e83 in ?? () from /usr/lib/libQtCore.so.4
#5  0xb765a885 in start_thread () from /lib/i686/libpthread.so.0
#6  0xb5e7057e in clone () from /lib/i686/libc.so.6

Thread 1 (Thread 0xb57ce6d0 (LWP 4470)):
[KCrash Handler]
#6  AbstractTaskItem::basicPreferredSize (this=0x949cd30) at /opt/kde/src/kdebase-workspace-4.3.4/plasma/applets/tasks/tasks.h:92
#7  0xa761b73b in TaskItemLayout::preferredColumns (this=0x8dec9b8) at /opt/kde/src/kdebase-workspace-4.3.4/plasma/applets/tasks/taskitemlayout.cpp:211
#8  0xa761c53a in TaskItemLayout::gridLayoutSize (this=0x8dec9b8) at /opt/kde/src/kdebase-workspace-4.3.4/plasma/applets/tasks/taskitemlayout.cpp:227
#9  0xa761c5fc in TaskItemLayout::layoutItems (this=0x8dec9b8) at /opt/kde/src/kdebase-workspace-4.3.4/plasma/applets/tasks/taskitemlayout.cpp:250
#10 0xa761d81a in TaskItemLayout::remove (this=0x8dec9b8, item=0x92cfd98) at /opt/kde/src/kdebase-workspace-4.3.4/plasma/applets/tasks/taskitemlayout.cpp:141
#11 0xa761da5c in TaskItemLayout::removeTaskItem (this=0x8dec9b8, item=0x92cfd98) at /opt/kde/src/kdebase-workspace-4.3.4/plasma/applets/tasks/taskitemlayout.cpp:93
#12 0xa76297ce in TaskGroupItem::itemRemoved (this=0x91a1830, groupableItem=0x94e75d0) at /opt/kde/src/kdebase-workspace-4.3.4/plasma/applets/tasks/taskgroupitem.cpp:521
#13 0xa762ac57 in TaskGroupItem::qt_metacall (this=0x91a1830, _c=QMetaObject::InvokeMetaMethod, _id=31, _a=0xbfacecf8)
    at /opt/kde/build/kdebase-workspace-4.3.4/plasma/applets/tasks/taskgroupitem.moc:114
#14 0xb77c6144 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#15 0xb77c6e65 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#16 0xa76c82c3 in TaskManager::TaskGroup::itemRemoved (this=0x91aa188, _t1=0x94e75d0) at /opt/kde/build/kdebase-workspace-4.3.4/libs/taskmanager/taskgroup.moc:152
#17 0xa76c8aeb in TaskManager::TaskGroup::remove (this=0x91aa188, item=0x94e75d0) at /opt/kde/src/kdebase-workspace-4.3.4/libs/taskmanager/taskgroup.cpp:189
#18 0xa76b056d in TaskManager::GroupManagerPrivate::removeTask (this=0x919c088, task={d = 0x9633418}) at /opt/kde/src/kdebase-workspace-4.3.4/libs/taskmanager/groupmanager.cpp:311
#19 0xa76b237b in TaskManager::GroupManager::qt_metacall (this=0x8e66bc8, _c=QMetaObject::InvokeMetaMethod, _id=11, _a=0xbfaceed8)
    at /opt/kde/build/kdebase-workspace-4.3.4/libs/taskmanager/groupmanager.moc:105
#20 0xb77c6144 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#21 0xb77c6e65 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#22 0xa76cbd23 in TaskManager::TaskManager::taskRemoved (this=0x8ded9d8, _t1={d = 0x9633418}) at /opt/kde/build/kdebase-workspace-4.3.4/libs/taskmanager/taskmanager.moc:162
#23 0xa76cdaa2 in TaskManager::TaskManager::windowRemoved (this=0x8ded9d8, w=42002555) at /opt/kde/src/kdebase-workspace-4.3.4/libs/taskmanager/taskmanager.cpp:278
#24 0xa76cf3ef in TaskManager::TaskManager::qt_metacall (this=0x8ded9d8, _c=QMetaObject::InvokeMetaMethod, _id=7, _a=0xbfacf058)
    at /opt/kde/build/kdebase-workspace-4.3.4/libs/taskmanager/taskmanager.moc:110
#25 0xb77c6144 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#26 0xb77c6e65 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#27 0xb6dad193 in KWindowSystem::windowRemoved (this=0x8b75eb8, _t1=42002555) at /opt/kde/build/kdelibs-4.3.4/kdeui/kwindowsystem.moc:127
#28 0xb6db0396 in KWindowSystemPrivate::removeClient (this=0x8b3dad0, w=42002555) at /opt/kde/src/kdelibs-4.3.4/kdeui/windowmanagement/kwindowsystem_x11.cpp:249
#29 0xb6dbe79f in NETRootInfo::update (this=0x8b3dae4, dirty_props=0xbfacf24c) at /opt/kde/src/kdelibs-4.3.4/kdeui/windowmanagement/netwm.cpp:2183
#30 0xb6dbf2e1 in NETRootInfo::event (this=0x8b3dae4, event=<value optimized out>, properties=0xbfacf2d4, properties_size=5) at /opt/kde/src/kdelibs-4.3.4/kdeui/windowmanagement/netwm.cpp:2058
#31 0xb6db0631 in KWindowSystemPrivate::x11Event (this=0x8b3dad0, ev=0xbfad08ac) at /opt/kde/src/kdelibs-4.3.4/kdeui/windowmanagement/kwindowsystem_x11.cpp:136
#32 0xb6c5e366 in KApplication::x11EventFilter (this=0x8992c78, _event=0xbfad08ac) at /opt/kde/src/kdelibs-4.3.4/kdeui/kernel/kapplication.cpp:900
#33 0xb317009f in PlasmaApp::x11EventFilter (this=0x8992c78, event=0xbfad08ac) at /opt/kde/src/kdebase-workspace-4.3.4/plasma/shells/desktop/plasmaapp.cpp:490
#34 0xb61a3951 in ?? () from /usr/lib/libQtGui.so.4
#35 0xb61b53ff in QApplication::x11ProcessEvent () from /usr/lib/libQtGui.so.4
#36 0xb61e1d88 in ?? () from /usr/lib/libQtGui.so.4
#37 0xb5ce9b92 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#38 0xb5ced468 in ?? () from /usr/lib/libglib-2.0.so.0
#39 0xb5ced58e in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#40 0xb77db8f1 in QEventDispatcherGlib::processEvents () from /usr/lib/libQtCore.so.4
#41 0xb61e14ba in ?? () from /usr/lib/libQtGui.so.4
#42 0xb77ae26d in QEventLoop::processEvents () from /usr/lib/libQtCore.so.4
#43 0xb77ae6b9 in QEventLoop::exec () from /usr/lib/libQtCore.so.4
#44 0xb77b0b50 in QCoreApplication::exec () from /usr/lib/libQtCore.so.4
#45 0xb613f504 in QApplication::exec () from /usr/lib/libQtGui.so.4
#46 0xb315a19d in kdemain (argc=1, argv=0x893c688) at /opt/kde/src/kdebase-workspace-4.3.4/plasma/shells/desktop/main.cpp:50
#47 0x0804d9d9 in launch (argc=<value optimized out>, _name=<value optimized out>, args=<value optimized out>, cwd=0x0, envc=0, envs=0x897eda4 "", reset_env=false, tty=0x0, avoid_loops=false, 
    startup_id_str=0x8050ac7 "0") at /opt/kde/src/kdelibs-4.3.4/kinit/kinit.cpp:677
#48 0x0804e54d in handle_launcher_request (sock=<value optimized out>, who=<value optimized out>) at /opt/kde/src/kdelibs-4.3.4/kinit/kinit.cpp:1169
#49 0x0804e9e4 in handle_requests (waitForPid=<value optimized out>) at /opt/kde/src/kdelibs-4.3.4/kinit/kinit.cpp:1362
#50 0x0804f1f7 in main (argc=2, argv=0xbfad1464, envp=0xbfad1470) at /opt/kde/src/kdelibs-4.3.4/kinit/kinit.cpp:1793

Reported using DrKonqi