Version:            (using Devel)
Compiler:          gcc version 4.3.2 (Gentoo 4.3.2 p1.0)  
OS:                Linux
Installed from:    Compiled sources

What I did:

1) logged out
2) krunner crashed (waited to save backtrace)
3) killed the X server (CTRL + Alt + Backspace)
3) logged in again
5) plasma crashed with the backtrace below

Application: Plasma Workspace (plasma), signal SIGSEGV
[Current thread is 0 (LWP 5479)]

Thread 3 (Thread 0xa9694b90 (LWP 5480)):
#0  0xffffe424 in __kernel_vsyscall ()
#1  0xb722ebe5 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
#2  0xb72aec8f in QWaitCondition::wait (this=0x82a0490, mutex=0x82a048c, time=4294967295) at thread/qwaitcondition_unix.cpp:88
#3  0xb7adb9a3 in QHostInfoAgent::run (this=0x82a0480) at kernel/qhostinfo.cpp:247
#4  0xb72ada24 in QThreadPrivate::start (arg=0x82a0480) at thread/qthread_unix.cpp:191
#5  0xb722b160 in start_thread (arg=0xa9694b90) at pthread_create.c:297
#6  0xb6661c0e in clone () from /lib/libc.so.6

Thread 2 (Thread 0xa8d97b90 (LWP 5481)):
#0  0xffffe424 in __kernel_vsyscall ()
#1  0xb722ebe5 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
#2  0xb72aec8f in QWaitCondition::wait (this=0x81192b0, mutex=0x81192ac, time=4294967295) at thread/qwaitcondition_unix.cpp:88
#3  0xa97bdee4 in RenderThread::run (this=0x81192a4) at /var/tmp/portage/kde-base/plasma-workspace-4.1.73/work/plasma-workspace-4.1.73/plasma/wallpapers/image/renderthread.cpp:90
#4  0xb72ada24 in QThreadPrivate::start (arg=0x81192a4) at thread/qthread_unix.cpp:191
#5  0xb722b160 in start_thread (arg=0xa8d97b90) at pthread_create.c:297
#6  0xb6661c0e in clone () from /lib/libc.so.6

Thread 1 (Thread 0xb4a1d720 (LWP 5479)):
[KCrash Handler]
#6  QHash<KSharedPtr<TaskManager::Startup>, TaskManager::TaskItem*>::erase (this=0x82228c0, it={i = 0x8488c08}) at /usr/include/qt4/QtCore/qhash.h:815
#7  0xa98864f4 in QMutableHashIterator<KSharedPtr<TaskManager::Startup>, TaskManager::TaskItem*>::remove (this=0xbf98af98) at /usr/include/qt4/QtCore/qhash.h:1013
#8  0xa98838b0 in TaskManager::GroupManager::add (this=0x8175698, task={d = 0xbf98b018})
    at /var/tmp/portage/kde-base/libtaskmanager-4.1.73/work/libtaskmanager-4.1.73/libs/taskmanager/groupmanager.cpp:239
#9  0xa9884890 in TaskManager::GroupManager::qt_metacall (this=0x8175698, _c=QMetaObject::InvokeMetaMethod, _id=2, _a=0xbf98b0fc)
    at /var/tmp/portage/kde-base/libtaskmanager-4.1.73/work/libtaskmanager_build/libs/taskmanager/groupmanager.moc:87
#10 0xb73b54e1 in QMetaObject::activate (sender=0x8154820, from_signal_index=<value optimized out>, to_signal_index=4, argv=0xbf98b0fc) at kernel/qobject.cpp:3028
#11 0xb73b73d8 in QMetaObject::activate (sender=0x8154820, m=0xa98abbf8, local_signal_index=0, argv=0xbf98b0fc) at kernel/qobject.cpp:3098
#12 0xa989df2b in TaskManager::TaskManager::taskAdded (this=0x8154820, _t1={d = 0xbf98b158})
    at /var/tmp/portage/kde-base/libtaskmanager-4.1.73/work/libtaskmanager_build/libs/taskmanager/taskmanager.moc:147
#13 0xa989ee64 in TaskManager::TaskManager::windowAdded (this=0x8154820, w=58720257) at /var/tmp/portage/kde-base/libtaskmanager-4.1.73/work/libtaskmanager-4.1.73/libs/taskmanager/taskmanager.cpp:255
#14 0xa989f2d9 in TaskManager::TaskManager::qt_metacall (this=0x8154820, _c=QMetaObject::InvokeMetaMethod, _id=6, _a=0xbf98b2ac)
    at /var/tmp/portage/kde-base/libtaskmanager-4.1.73/work/libtaskmanager_build/libs/taskmanager/taskmanager.moc:104
#15 0xb73b54e1 in QMetaObject::activate (sender=0x80d1ad8, from_signal_index=<value optimized out>, to_signal_index=5, argv=0xbf98b2ac) at kernel/qobject.cpp:3028
#16 0xb73b73d8 in QMetaObject::activate (sender=0x80d1ad8, m=0xb7a2832c, local_signal_index=1, argv=0xbf98b2ac) at kernel/qobject.cpp:3098
#17 0xb79cd3ad in KWindowSystem::windowAdded (this=0x80d1ad8, _t1=58720257) at /var/tmp/portage/kde-base/kdelibs-4.1.73/work/kdelibs_build/kdeui/kwindowsystem.moc:118
#18 0xb79cf881 in KWindowSystemPrivate::addClient (this=0x80bc398, w=58720257) at /var/tmp/portage/kde-base/kdelibs-4.1.73/work/kdelibs-4.1.73/kdeui/windowmanagement/kwindowsystem_x11.cpp:229
#19 0xb79dc854 in NETRootInfo::update (this=0x80bc3ac, dirty_props=0xbf98b458) at /var/tmp/portage/kde-base/kdelibs-4.1.73/work/kdelibs-4.1.73/kdeui/windowmanagement/netwm.cpp:2114
#20 0xb79dcb2f in NETRootInfo::event (this=0x80bc3ac, event=0xbf98ba98, properties=0xbf98b4d4, properties_size=5)
    at /var/tmp/portage/kde-base/kdelibs-4.1.73/work/kdelibs-4.1.73/kdeui/windowmanagement/netwm.cpp:2043
#21 0xb79cfd49 in KWindowSystemPrivate::x11Event (this=0x80bc398, ev=0xbf98ba38) at /var/tmp/portage/kde-base/kdelibs-4.1.73/work/kdelibs-4.1.73/kdeui/windowmanagement/kwindowsystem_x11.cpp:136
#22 0xb78b98a5 in KAppX11HackWidget::publicx11Event (this=0x80bc398, e=0xbf98ba38) at /var/tmp/portage/kde-base/kdelibs-4.1.73/work/kdelibs-4.1.73/kdeui/kernel/kapplication.cpp:947
#23 0xb78b687c in KApplication::x11EventFilter (this=0x805d300, _event=0xbf98ba38) at /var/tmp/portage/kde-base/kdelibs-4.1.73/work/kdelibs-4.1.73/kdeui/kernel/kapplication.cpp:997
#24 0xb804d66b in PlasmaApp::x11EventFilter (this=0x805d300, event=0xbf98ba38)
    at /var/tmp/portage/kde-base/plasma-workspace-4.1.73/work/plasma-workspace-4.1.73/plasma/shells/desktop/plasmaapp.cpp:339
#25 0xb6abd21c in qt_x11EventFilter (ev=0xbf98ba38) at kernel/qapplication_x11.cpp:367
#26 0xb6accc19 in QApplication::x11ProcessEvent (this=0x805d300, event=0xbf98ba38) at kernel/qapplication_x11.cpp:2924
#27 0xb6af396d in QEventDispatcherX11::processEvents (this=0x805d6d0, flags={i = -1080509736}) at kernel/qeventdispatcher_x11.cpp:134
#28 0xb739d6b0 in QEventLoop::processEvents (this=0xbf98bb50, flags={i = -1080509672}) at kernel/qeventloop.cpp:149
#29 0xb739d852 in QEventLoop::exec (this=0xbf98bb50, flags={i = -1080509608}) at kernel/qeventloop.cpp:200
#30 0xb739fc6f in QCoreApplication::exec () at kernel/qcoreapplication.cpp:851
#31 0xb6a5dd43 in QApplication::exec () at kernel/qapplication.cpp:3337
#32 0xb803e146 in kdemain (argc=1, argv=0xbf98bd44) at /var/tmp/portage/kde-base/plasma-workspace-4.1.73/work/plasma-workspace-4.1.73/plasma/shells/desktop/main.cpp:58
#33 0x080487d2 in main (argc=0, argv=0x8481dc0) at /var/tmp/portage/kde-base/plasma-workspace-4.1.73/work/plasma-workspace_build/plasma/shells/desktop/plasma_qgv_dummy.cpp:3