Application: plasma-desktop (0.4)
KDE Platform Version: 4.7.4 (4.7.4)
Qt Version: 4.7.4
Operating System: Linux 3.0.0-16-generic x86_64
Distribution: Ubuntu 11.10

-- Information about the crash:
- What I was doing when the application crashed:

KDE starts up fine with 4 virtual desktops configured in a 2-display (xnierama) set up.
I tend to have one main application per visual desktop on one of the displays.
I switch between desktops using the mouse wheel.

- Unusual behavior I noticed:

Plasma desktop does not per se crash on all virtual desktops.
Plasma desktop just dies on my active virtual desktop switching without switchinga t times.

Quite frequently (guaranteed to happen several times during a workday) plasma is dead on the virtual desktop I switch to (black screen, no background, panels gone, although kwin seems to be there ). 
Stuff will reload though, although the taskswitcher in the panel bugs out and won't (re)load anymore.

The crash can be reproduced some of the time.

-- Backtrace:
Application: Plasma Desktop Shell (plasma-desktop), signal: Segmentation fault
[Current thread is 1 (Thread 0x7f0a282437a0 (LWP 23372))]

Thread 4 (Thread 0x7f0a0b7d0700 (LWP 23373)):
#0  timerSourcePrepare (source=0x7f0a04001e70, timeout=0x7f0a0b7cfc1c) at kernel/qeventdispatcher_glib.cpp:160
#1  0x00007f0a1be5bff2 in g_main_context_prepare () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007f0a1be5cdfd in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007f0a1be5d429 in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007f0a24d04f3e in QEventDispatcherGlib::processEvents (this=0x2e56890, flags=<optimized out>) at kernel/qeventdispatcher_glib.cpp:424
#5  0x00007f0a24cd8cf2 in QEventLoop::processEvents (this=<optimized out>, flags=...) at kernel/qeventloop.cpp:149
#6  0x00007f0a24cd8ef7 in QEventLoop::exec (this=0x7f0a0b7cfdb0, flags=...) at kernel/qeventloop.cpp:201
#7  0x00007f0a24bf027f in QThread::exec (this=<optimized out>) at thread/qthread.cpp:498
#8  0x00007f0a24cbbcbf in QInotifyFileSystemWatcherEngine::run (this=0x2e54bc0) at io/qfilesystemwatcher_inotify.cpp:248
#9  0x00007f0a24bf2d05 in QThreadPrivate::start (arg=0x2e54bc0) at thread/qthread_unix.cpp:331
#10 0x00007f0a1c969efc in start_thread (arg=0x7f0a0b7d0700) at pthread_create.c:304
#11 0x00007f0a27b2489d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#12 0x0000000000000000 in ?? ()

Thread 3 (Thread 0x7f0a08f9c700 (LWP 23374)):
#0  0x00007f0a1c96d1fd in __pthread_mutex_unlock_usercnt (mutex=<optimized out>, decr=<optimized out>) at pthread_mutex_unlock.c:52
#1  __pthread_mutex_unlock (mutex=0x2f21928) at pthread_mutex_unlock.c:290
#2  0x00007f0a1be5d451 in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007f0a24d04f3e in QEventDispatcherGlib::processEvents (this=0x2dc3090, flags=<optimized out>) at kernel/qeventdispatcher_glib.cpp:424
#4  0x00007f0a24cd8cf2 in QEventLoop::processEvents (this=<optimized out>, flags=...) at kernel/qeventloop.cpp:149
#5  0x00007f0a24cd8ef7 in QEventLoop::exec (this=0x7f0a08f9bdb0, flags=...) at kernel/qeventloop.cpp:201
#6  0x00007f0a24bf027f in QThread::exec (this=<optimized out>) at thread/qthread.cpp:498
#7  0x00007f0a24cbbcbf in QInotifyFileSystemWatcherEngine::run (this=0x2f1f810) at io/qfilesystemwatcher_inotify.cpp:248
#8  0x00007f0a24bf2d05 in QThreadPrivate::start (arg=0x2f1f810) at thread/qthread_unix.cpp:331
#9  0x00007f0a1c969efc in start_thread (arg=0x7f0a08f9c700) at pthread_create.c:304
#10 0x00007f0a27b2489d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#11 0x0000000000000000 in ?? ()

Thread 2 (Thread 0x7f09f8735700 (LWP 23384)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:162
#1  0x00007f0a21d08fe2 in ?? () from /usr/lib/x86_64-linux-gnu/libQtScript.so.4
#2  0x00007f0a21d09019 in ?? () from /usr/lib/x86_64-linux-gnu/libQtScript.so.4
#3  0x00007f0a1c969efc in start_thread (arg=0x7f09f8735700) at pthread_create.c:304
#4  0x00007f0a27b2489d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#5  0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7f0a282437a0 (LWP 23372)):
[KCrash Handler]
#6  KWindowInfo::valid (this=0x4047000000000010, withdrawn_is_valid=true) at ../../kdeui/windowmanagement/kwindowinfo_x11.cpp:133
#7  0x00007f0a0efc84d6 in TaskManager::Task::isOnCurrentDesktop (this=0x563df00) at ../../../libs/taskmanager/task.cpp:211
#8  0x00007f09f7a7cc64 in TaskSource::updateDesktop (this=0x4a802e0, desktop=<optimized out>) at ../../../../../plasma/generic/dataengines/tasks/tasksource.cpp:161
#9  0x00007f09f7a7cfc3 in TaskSource::qt_metacall (this=0x4a802e0, _c=QMetaObject::InvokeMetaMethod, _id=<optimized out>, _a=0x7ffffb28f430) at ./tasksource.moc:82
#10 0x00007f0a24ceceba in QMetaObject::activate (sender=0x2fa7aa0, m=<optimized out>, local_signal_index=<optimized out>, argv=0x7ffffb28f430) at kernel/qobject.cpp:3278
#11 0x00007f0a0efd46f1 in TaskManager::TaskManager::desktopChanged (this=<optimized out>, _t1=2) at ./taskmanager.moc:200
#12 0x00007f0a0efd6237 in TaskManager::TaskManager::qt_metacall (this=0x2fa7aa0, _c=QMetaObject::InvokeMetaMethod, _id=11, _a=0x7ffffb28f600) at ./taskmanager.moc:127
#13 0x00007f0a24ceceba in QMetaObject::activate (sender=0x2560340, m=<optimized out>, local_signal_index=<optimized out>, argv=0x7ffffb28f600) at kernel/qobject.cpp:3278
#14 0x00007f0a25abf76e in KWindowSystem::currentDesktopChanged (this=<optimized out>, _t1=2) at ./kwindowsystem.moc:122
#15 0x00007f0a25ac1c63 in KWindowSystemPrivate::x11Event (this=0x25bda20, ev=0x7ffffb28f710) at ../../kdeui/windowmanagement/kwindowsystem_x11.cpp:175
#16 0x00007f0a259b13e6 in publicX11Event (e=0x7ffffb28f710, this=<optimized out>) at ../../kdeui/kernel/ksystemeventfilter.cpp:43
#17 KSystemEventFilterPrivate::filterEvent (this=0x25e9db0, message=0x7ffffb28f710) at ../../kdeui/kernel/ksystemeventfilter.cpp:102
#18 0x00007f0a24131418 in x11EventSourceDispatch (s=0x24be920, callback=0, user_data=0x0) at kernel/qguieventdispatcher_glib.cpp:143
#19 0x00007f0a1be5ca5d in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#20 0x00007f0a1be5d258 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#21 0x00007f0a1be5d429 in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#22 0x00007f0a24d04ed6 in QEventDispatcherGlib::processEvents (this=0x2441f40, flags=<optimized out>) at kernel/qeventdispatcher_glib.cpp:422
#23 0x00007f0a2413110e in QGuiEventDispatcherGlib::processEvents (this=<optimized out>, flags=<optimized out>) at kernel/qguieventdispatcher_glib.cpp:204
#24 0x00007f0a24cd8cf2 in QEventLoop::processEvents (this=<optimized out>, flags=...) at kernel/qeventloop.cpp:149
#25 0x00007f0a24cd8ef7 in QEventLoop::exec (this=0x7ffffb28fae0, flags=...) at kernel/qeventloop.cpp:201
#26 0x00007f0a24cdd789 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1064
#27 0x00007f0a27e231a3 in kdemain (argc=1, argv=0x7ffffb28fec8) at ../../../../plasma/desktop/shell/main.cpp:120
#28 0x00007f0a27a6430d in __libc_start_main (main=0x400640 <main(int, char**)>, argc=1, ubp_av=0x7ffffb28fec8, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7ffffb28feb8) at libc-start.c:226
#29 0x0000000000400671 in _start ()

Possible duplicates by query: bug 291700, bug 290829, bug 290024, bug 289611, bug 289461.

Reported using DrKonqi