Application that crashed: plasma-desktop
Version of the application: 0.3
KDE Version: 4.3.2 (KDE 4.3.2)
Qt Version: 4.5.2
Operating System: Linux 2.6.31-16-generic x86_64
Distribution: Ubuntu 9.10

What I was doing when the application crashed:
when I switch between virtual destops the plasma-desktop crash randomly.
usually the crash handler pop up and the plasma-desktop restarting before I push the 'Restart' button on crash handler.

some times the crash handler doesn't pop up and plasma-desktop doesn't restart  but in this case it also can be started via ALT+F2 or from konsole.

 -- Backtrace:
Application: Plasma Workspace (kdeinit4), signal: Segmentation fault
[Current thread is 1 (Thread 0x7f7b6dc72750 (LWP 2536))]

Thread 2 (Thread 0x7f7b527b5910 (LWP 2611)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:261
#1  0x00007f7b6d6b84fb in QWaitCondition::wait(QMutex*, unsigned long) () from /usr/lib/libQtCore.so.4
#2  0x00007f7b69aef78c in ?? () from /usr/lib/libQtNetwork.so.4
#3  0x00007f7b6d6b7445 in ?? () from /usr/lib/libQtCore.so.4
#4  0x00007f7b6a42da04 in start_thread (arg=<value optimized out>) at pthread_create.c:300
#5  0x00007f7b6b00d7bd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#6  0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7f7b6dc72750 (LWP 2536)):
[KCrash Handler]
#5  0x0000000000000024 in ?? ()
#6  0x00007f7b6bce513a in QGraphicsItem::setParentItem(QGraphicsItem*) () from /usr/lib/libQtGui.so.4
#7  0x00007f7b6bd34bfa in QGraphicsGridLayout::addItem(QGraphicsLayoutItem*, int, int, int, int, QFlags<Qt::AlignmentFlag>) () from /usr/lib/libQtGui.so.4
#8  0x00007f7b54df335d in ?? () from /usr/lib/kde4/plasma_applet_tasks.so
#9  0x00007f7b54df3a4f in ?? () from /usr/lib/kde4/plasma_applet_tasks.so
#10 0x00007f7b54df3c20 in ?? () from /usr/lib/kde4/plasma_applet_tasks.so
#11 0x00007f7b54dff948 in ?? () from /usr/lib/kde4/plasma_applet_tasks.so
#12 0x00007f7b54dfffc4 in ?? () from /usr/lib/kde4/plasma_applet_tasks.so
#13 0x00007f7b6d7b2ddc in QMetaObject::activate(QObject*, int, int, void**) () from /usr/lib/libQtCore.so.4
#14 0x00007f7b54bc4d6f in TaskManager::TaskGroup::itemAdded(TaskManager::AbstractGroupableItem*) () from /usr/lib/libtaskmanager.so.4
#15 0x00007f7b54bc565f in TaskManager::TaskGroup::add(TaskManager::AbstractGroupableItem*) () from /usr/lib/libtaskmanager.so.4
#16 0x00007f7b54baefd4 in ?? () from /usr/lib/libtaskmanager.so.4
#17 0x00007f7b54baf8bb in ?? () from /usr/lib/libtaskmanager.so.4
#18 0x00007f7b54bb1139 in TaskManager::GroupManager::qt_metacall(QMetaObject::Call, int, void**) () from /usr/lib/libtaskmanager.so.4
#19 0x00007f7b6d7b2ddc in QMetaObject::activate(QObject*, int, int, void**) () from /usr/lib/libQtCore.so.4
#20 0x00007f7b6d7acd83 in QObject::event(QEvent*) () from /usr/lib/libQtCore.so.4
#21 0x00007f7b6b74defc in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#22 0x00007f7b6b7551ce in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#23 0x00007f7b6c384ab6 in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#24 0x00007f7b6d79dc2c in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#25 0x00007f7b6d7c8862 in ?? () from /usr/lib/libQtCore.so.4
#26 0x00007f7b6d7c625d in ?? () from /usr/lib/libQtCore.so.4
#27 0x00007f7b6a67ebce in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#28 0x00007f7b6a682598 in ?? () from /lib/libglib-2.0.so.0
#29 0x00007f7b6a6826c0 in g_main_context_iteration () from /lib/libglib-2.0.so.0
#30 0x00007f7b6d7c61a6 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#31 0x00007f7b6b7e24be in ?? () from /usr/lib/libQtGui.so.4
#32 0x00007f7b6d79c532 in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#33 0x00007f7b6d79c904 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#34 0x00007f7b6d79eab9 in QCoreApplication::exec() () from /usr/lib/libQtCore.so.4
#35 0x00007f7b628344cf in kdemain () from /usr/lib/libkdeinit4_plasma-desktop.so
#36 0x0000000000406da8 in _start ()
The current source language is "auto; currently asm".
The current source language is "auto; currently c".

Reported using DrKonqi