Application: plasma-desktop (0.3)
KDE Platform Version: 4.3.80 (KDE 4.3.80 (KDE 4.4 Beta1))
Qt Version: 4.6.0
Operating System: Linux 2.6.31-ARCH i686
Distribution (Platform): Archlinux Packages

-- Information about the crash:
i've upgraded to kde 4.4 beta 1 (kdemod on archlinux) and this crash occured after i restarted X. most apps seem to run, just plasma desktop and taskbar are missing. 

 -- Backtrace:
Application: Plasma Workspace (kdeinit4), signal: Segmentation fault
[Current thread is 1 (Thread 0xb53a8920 (LWP 7021))]

Thread 3 (Thread 0xa783db70 (LWP 7025)):
#0  0xb7798424 in __kernel_vsyscall ()
#1  0xb74e1e65 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
#2  0xb3542a97 in ?? () from /usr/lib/libQtScript.so.4
#3  0xb3542ae1 in ?? () from /usr/lib/libQtScript.so.4
#4  0xb74dd8ac in start_thread () from /lib/libpthread.so.0
#5  0xb5e4ca9e in clone () from /lib/libc.so.6

Thread 2 (Thread 0xa6a10b70 (LWP 7026)):
#0  0xb7798424 in __kernel_vsyscall ()
#1  0xb74e1e65 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
#2  0xb75573f7 in QWaitCondition::wait(QMutex*, unsigned long) () from /usr/lib/libQtCore.so.4
#3  0xb5bc87a2 in ?? () from /usr/lib/libQtNetwork.so.4
#4  0xb75564be in ?? () from /usr/lib/libQtCore.so.4
#5  0xb74dd8ac in start_thread () from /lib/libpthread.so.0
#6  0xb5e4ca9e in clone () from /lib/libc.so.6

Thread 1 (Thread 0xb53a8920 (LWP 7021)):
[KCrash Handler]
#6  0x00000000 in ?? ()
#7  0xb76691f2 in QObject::connect(QObject const*, char const*, QObject const*, char const*, Qt::ConnectionType) () from /usr/lib/libQtCore.so.4
#8  0xa7bac4f2 in SmoothTasks::Task::Task(TaskManager::AbstractGroupableItem*, QObject*) () from /usr/lib/kde4/plasma_applet_smooth-tasks.so
#9  0xa7bb0e9d in SmoothTasks::TaskItem::TaskItem(TaskManager::AbstractGroupableItem*, SmoothTasks::Applet*) () from /usr/lib/kde4/plasma_applet_smooth-tasks.so
#10 0xa7b9d3ed in SmoothTasks::Applet::itemAdded(TaskManager::AbstractGroupableItem*) () from /usr/lib/kde4/plasma_applet_smooth-tasks.so
#11 0xa7ba1f17 in SmoothTasks::Applet::qt_metacall(QMetaObject::Call, int, void**) () from /usr/lib/kde4/plasma_applet_smooth-tasks.so
#12 0xb765be7a in QMetaObject::metacall(QObject*, QMetaObject::Call, int, void**) () from /usr/lib/libQtCore.so.4
#13 0xb766a44d in QMetaObject::activate(QObject*, QMetaObject const*, int, void**) () from /usr/lib/libQtCore.so.4
#14 0xa7b71303 in TaskManager::TaskGroup::itemAdded(TaskManager::AbstractGroupableItem*) () from /usr/lib/libtaskmanager.so.4
#15 0xa7b72333 in TaskManager::TaskGroup::add(TaskManager::AbstractGroupableItem*) () from /usr/lib/libtaskmanager.so.4
#16 0xa7b5e939 in TaskManager::GroupManagerPrivate::addTask(KSharedPtr<TaskManager::Task>) () from /usr/lib/libtaskmanager.so.4
#17 0xa7b5fa33 in TaskManager::GroupManager::qt_metacall(QMetaObject::Call, int, void**) () from /usr/lib/libtaskmanager.so.4
#18 0xb765be7a in QMetaObject::metacall(QObject*, QMetaObject::Call, int, void**) () from /usr/lib/libQtCore.so.4
#19 0xb766a44d in QMetaObject::activate(QObject*, QMetaObject const*, int, void**) () from /usr/lib/libQtCore.so.4
#20 0xa7b76153 in TaskManager::TaskManager::taskAdded(KSharedPtr<TaskManager::Task>) () from /usr/lib/libtaskmanager.so.4
#21 0xa7b783f3 in TaskManager::TaskManager::windowAdded(unsigned long) () from /usr/lib/libtaskmanager.so.4
#22 0xa7b799bf in TaskManager::TaskManager::qt_metacall(QMetaObject::Call, int, void**) () from /usr/lib/libtaskmanager.so.4
#23 0xb765be7a in QMetaObject::metacall(QObject*, QMetaObject::Call, int, void**) () from /usr/lib/libQtCore.so.4
#24 0xb766a44d in QMetaObject::activate(QObject*, QMetaObject const*, int, void**) () from /usr/lib/libQtCore.so.4
#25 0xb6d5b1c3 in KWindowSystem::windowAdded(unsigned long) () from /usr/lib/libkdeui.so.5
#26 0xb6d5e2b6 in KWindowSystemPrivate::addClient(unsigned long) () from /usr/lib/libkdeui.so.5
#27 0xb6d6cb07 in NETRootInfo::update(unsigned long const*) () from /usr/lib/libkdeui.so.5
#28 0xb6d6d612 in NETRootInfo::event(_XEvent*, unsigned long*, int) () from /usr/lib/libkdeui.so.5
#29 0xb6d5e6a1 in KWindowSystemPrivate::x11Event(_XEvent*) () from /usr/lib/libkdeui.so.5
#30 0xb6bfdee6 in KApplication::x11EventFilter(_XEvent*) () from /usr/lib/libkdeui.so.5
#31 0xb36f156f in PlasmaApp::x11EventFilter(_XEvent*) () from /usr/lib/libkdeinit4_plasma-desktop.so
#32 0xb616c3f0 in ?? () from /usr/lib/libQtGui.so.4
#33 0xb617b8be in QApplication::x11ProcessEvent(_XEvent*) () from /usr/lib/libQtGui.so.4
#34 0xb61a9c52 in ?? () from /usr/lib/libQtGui.so.4
#35 0xb5cdd328 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#36 0xb5ce0ba0 in g_main_context_iterate () from /usr/lib/libglib-2.0.so.0
#37 0xb5ce0cd3 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#38 0xb76826e5 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#39 0xb61a97b5 in ?? () from /usr/lib/libQtGui.so.4
#40 0xb76552a9 in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#41 0xb76556fa in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#42 0xb765986f in QCoreApplication::exec() () from /usr/lib/libQtCore.so.4
#43 0xb60eecb7 in QApplication::exec() () from /usr/lib/libQtGui.so.4
#44 0xb36dd41e in kdemain () from /usr/lib/libkdeinit4_plasma-desktop.so
#45 0x0804dff2 in _start ()

Reported using DrKonqi