Version:            (using KDE 4.2.0)
OS:                Linux
Installed from:    Fedora RPMs

Sometimes plasma crashes (SIGSEGV) on login. See the backtrace (I will attach two more (older ones)):

Application: Plasma Workspace (plasma), signal SIGSEGV
0x00007f9ed4328f81 in nanosleep () from /lib64/libc.so.6
Current language:  auto; currently c
[Current thread is 1 (Thread 0x7f9ecc5ac840 (LWP 2855))]

Thread 3 (Thread 0x7f9eb361f950 (LWP 2862)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:261
#1  0x00007f9ed5010839 in QWaitConditionPrivate::wait () at thread/qwaitcondition_unix.cpp:82
#2  QWaitCondition::wait (this=0x1d0d500, mutex=0x1d0d4f8, time=18446744073709551615) at thread/qwaitcondition_unix.cpp:154
#3  0x0000000001f5deac in QHostInfoAgent::run (this=0x1d0d4e0) at kernel/qhostinfo.cpp:241
#4  0x00007f9ed500f852 in QThreadPrivate::start (arg=0x1d0d4e0) at thread/qthread_unix.cpp:185
#5  0x00007f9ed4da13da in start_thread (arg=<value optimized out>) at pthread_create.c:297
#6  0x00007f9ed43672bd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112

Thread 2 (Thread 0x7f9eb13b4950 (LWP 2892)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:261
#1  0x00007f9ed5010839 in QWaitConditionPrivate::wait () at thread/qwaitcondition_unix.cpp:82
#2  QWaitCondition::wait (this=0x1adfaf0, mutex=0x1adfae8, time=18446744073709551615) at thread/qwaitcondition_unix.cpp:154
#3  0x00007f9eb6050fa0 in RenderThread::run (this=0x1adfad8) at /usr/src/debug/kdebase-workspace-4.2.0/plasma/wallpapers/image/renderthread.cpp:91
#4  0x00007f9ed500f852 in QThreadPrivate::start (arg=0x1adfad8) at thread/qthread_unix.cpp:185
#5  0x00007f9ed4da13da in start_thread (arg=<value optimized out>) at pthread_create.c:297
#6  0x00007f9ed43672bd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
Current language:  auto; currently asm

Thread 1 (Thread 0x7f9ecc5ac840 (LWP 2855)):
[KCrash Handler]
#5  QHash<KSharedPtr<TaskManager::Startup>, TaskManager::TaskItem*>::erase () at /usr/include/QtCore/qhash.h:809
#6  QMutableHashIterator<KSharedPtr<TaskManager::Startup>, TaskManager::TaskItem*>::remove () at /usr/include/QtCore/qhash.h:1007
#7  TaskManager::GroupManager::add (this=0x1e04fc0, task=) at /usr/src/debug/kdebase-workspace-4.2.0/libs/taskmanager/groupmanager.cpp:241
#8  0x00007f9eb75cc51b in TaskManager::GroupManager::qt_metacall (this=0x1e04fc0, _c=<value optimized out>, _id=<value optimized out>, _a=0x7fffdfaef010)
    at /usr/src/debug/kdebase-workspace-4.2.0/x86_64-redhat-linux-gnu/libs/taskmanager/groupmanager.moc:90
#9  0x00007f9ed510c764 in QMetaObject::activate (sender=0x1af5010, from_signal_index=<value optimized out>, to_signal_index=4, argv=0x7f9eb25a1d80) at kernel/qobject.cpp:3031
#10 0x00007f9eb75e0bf2 in TaskManager::TaskManager::taskAdded (this=0x7f9eb0283bb0, _t1=<value optimized out>)
    at /usr/src/debug/kdebase-workspace-4.2.0/x86_64-redhat-linux-gnu/libs/taskmanager/taskmanager.moc:150
#11 0x00007f9eb75e2c3f in TaskManager::TaskManager::windowAdded (this=0x1af5010, w=62914663) at /usr/src/debug/kdebase-workspace-4.2.0/libs/taskmanager/taskmanager.cpp:246
#12 0x00007f9eb75e3c2f in TaskManager::TaskManager::qt_metacall (this=0x1af5010, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0x7fffdfaef2a0)
    at /usr/src/debug/kdebase-workspace-4.2.0/x86_64-redhat-linux-gnu/libs/taskmanager/taskmanager.moc:106
#13 0x00007f9ed510c764 in QMetaObject::activate (sender=0x170ec80, from_signal_index=<value optimized out>, to_signal_index=5, argv=0x7f9eb25a1d80) at kernel/qobject.cpp:3031
#14 0x00007f9ed7806e82 in KWindowSystem::windowAdded () from /usr/lib64/libkdeui.so.5
#15 0x00007f9ed78091dc in ?? () from /usr/lib64/libkdeui.so.5
#16 0x00007f9ed78181fb in NETRootInfo::update () from /usr/lib64/libkdeui.so.5
#17 0x00007f9ed781855b in NETRootInfo::event () from /usr/lib64/libkdeui.so.5
#18 0x00007f9ed780965b in ?? () from /usr/lib64/libkdeui.so.5
#19 0x00007f9ed76e4203 in KApplication::x11EventFilter () from /usr/lib64/libkdeui.so.5
#20 0x0000000000151d34 in PlasmaApp::x11EventFilter (this=0x16f4c90, event=0x7fffdfaefee0) at /usr/src/debug/kdebase-workspace-4.2.0/plasma/shells/desktop/plasmaapp.cpp:453
#21 0x00007f9ed582149f in qt_x11EventFilter (ev=0x7fffdfaefee0) at kernel/qapplication_x11.cpp:361
#22 0x00007f9ed5832b56 in QApplication::x11ProcessEvent (this=0x16f4c90, event=0x7fffdfaefee0) at kernel/qapplication_x11.cpp:2922
#23 0x00007f9ed5859ae4 in x11EventSourceDispatch (s=0x1712830, callback=0, user_data=0x0) at kernel/qguieventdispatcher_glib.cpp:142
#24 0x00007f9ed13eb79b in g_main_dispatch () at gmain.c:2144
#25 IA__g_main_context_dispatch (context=0x1711990) at gmain.c:2697
#26 0x00007f9ed13eef6d in g_main_context_iterate (context=0x1711990, block=1, dispatch=1, self=<value optimized out>) at gmain.c:2778
#27 0x00007f9ed13ef12b in IA__g_main_context_iteration (context=0x1711990, may_block=1) at gmain.c:2841
#28 0x00007f9ed512079f in QEventDispatcherGlib::processEvents (this=0x1705090, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:319
#29 0x00007f9ed585928f in QGuiEventDispatcherGlib::processEvents (this=0x7f9eb0283bb0, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:198
#30 0x00007f9ed50f6cb2 in QEventLoop::processEvents (this=<value optimized out>, flags=) at kernel/qeventloop.cpp:143
#31 0x00007f9ed50f6e3d in QEventLoop::exec (this=0x7fffdfaf0210, flags=) at kernel/qeventloop.cpp:194
#32 0x00007f9ed50f92ed in QCoreApplication::exec () at kernel/qcoreapplication.cpp:845
#33 0x00000000001439bb in kdemain (argc=1, argv=0x7fffdfaf0518) at /usr/src/debug/kdebase-workspace-4.2.0/plasma/shells/desktop/main.cpp:54
#34 0x00007f9ed429f576 in __libc_start_main (main=0x400830 <main>, argc=1, ubp_av=0x7fffdfaf0518, init=0x400860 <__libc_csu_init>, fini=<value optimized out>, rtld_fini=<value optimized out>, 
    stack_end=0x7fffdfaf0508) at libc-start.c:220
#35 0x0000000000400769 in _start ()
Current language:  auto; currently c