Application: plasma-desktop (0.4)
KDE Platform Version: 4.7.3 (4.7.3)
Qt Version: 4.7.4
Operating System: Linux 3.0.0-14-generic x86_64
Distribution: Ubuntu 11.10

-- Information about the crash:
Steps to repro:
1. KDE started
2. No apps were visible, only the Plasma background and the Lock/Logout widget
3. Alt-tab showed the apps in the selector (konsole, chrome etc..) from my previous session, but on selecting them in the alt-tab switcher, nothing came to the foreground.
4. I right-clicked 'Add Panel' -> 'Default Panel' and Plasma crashed, with the open apps now visible
5. Plasma restarted and hid my apps again.
6. I tried to add a default panel again and this time it crashed and did not restart.

-- Backtrace:
Application: Plasma Desktop Shell (plasma-desktop), signal: Segmentation fault
[Current thread is 1 (Thread 0x7f48b68777c0 (LWP 2307))]

Thread 4 (Thread 0x7f48939e5700 (LWP 2309)):
#0  0x00007f48b615f773 in __GI___poll (fds=<optimized out>, nfds=<optimized out>, timeout=<optimized out>) at ../sysdeps/unix/sysv/linux/poll.c:87
#1  0x00007f48aa6e9f68 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007f48aa6ea429 in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007f48b3350f3e in QEventDispatcherGlib::processEvents (this=0x3740620, flags=<optimized out>) at kernel/qeventdispatcher_glib.cpp:424
#4  0x00007f48b3324cf2 in QEventLoop::processEvents (this=<optimized out>, flags=...) at kernel/qeventloop.cpp:149
#5  0x00007f48b3324ef7 in QEventLoop::exec (this=0x7f48939e4cd0, flags=...) at kernel/qeventloop.cpp:201
#6  0x00007f48b323c27f in QThread::exec (this=<optimized out>) at thread/qthread.cpp:498
#7  0x00007f48b3307cbf in QInotifyFileSystemWatcherEngine::run (this=0x374c6c0) at io/qfilesystemwatcher_inotify.cpp:248
#8  0x00007f48b323ed05 in QThreadPrivate::start (arg=0x374c6c0) at thread/qthread_unix.cpp:331
#9  0x00007f48a7a0356c in ?? () from /usr/lib/nvidia-current/libGL.so.1
#10 0x00007f48ab1f6efc in start_thread (arg=0x7f48939e5700) at pthread_create.c:304
#11 0x00007f48b616b89d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#12 0x0000000000000000 in ?? ()

Thread 3 (Thread 0x7f48913bd700 (LWP 2311)):
#0  0x00007f48ab1fa1fd in __pthread_mutex_unlock_usercnt (mutex=<optimized out>, decr=<optimized out>) at pthread_mutex_unlock.c:52
#1  __pthread_mutex_unlock (mutex=0x37729d8) at pthread_mutex_unlock.c:290
#2  0x00007f48aa6e8fe4 in g_main_context_prepare () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007f48aa6e9dfd in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007f48aa6ea429 in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#5  0x00007f48b3350f3e in QEventDispatcherGlib::processEvents (this=0x2d993b0, flags=<optimized out>) at kernel/qeventdispatcher_glib.cpp:424
#6  0x00007f48b3324cf2 in QEventLoop::processEvents (this=<optimized out>, flags=...) at kernel/qeventloop.cpp:149
#7  0x00007f48b3324ef7 in QEventLoop::exec (this=0x7f48913bccd0, flags=...) at kernel/qeventloop.cpp:201
#8  0x00007f48b323c27f in QThread::exec (this=<optimized out>) at thread/qthread.cpp:498
#9  0x00007f48b3307cbf in QInotifyFileSystemWatcherEngine::run (this=0x257fc00) at io/qfilesystemwatcher_inotify.cpp:248
#10 0x00007f48b323ed05 in QThreadPrivate::start (arg=0x257fc00) at thread/qthread_unix.cpp:331
#11 0x00007f48a7a0356c in ?? () from /usr/lib/nvidia-current/libGL.so.1
#12 0x00007f48ab1f6efc in start_thread (arg=0x7f48913bd700) at pthread_create.c:304
#13 0x00007f48b616b89d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#14 0x0000000000000000 in ?? ()

Thread 2 (Thread 0x7f488380d700 (LWP 3008)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:162
#1  0x00007f48b0355fe2 in ?? () from /usr/lib/x86_64-linux-gnu/libQtScript.so.4
#2  0x00007f48b0356019 in ?? () from /usr/lib/x86_64-linux-gnu/libQtScript.so.4
#3  0x00007f48a7a0356c in ?? () from /usr/lib/nvidia-current/libGL.so.1
#4  0x00007f48ab1f6efc in start_thread (arg=0x7f488380d700) at pthread_create.c:304
#5  0x00007f48b616b89d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#6  0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7f48b68777c0 (LWP 2307)):
[KCrash Handler]
#6  QGraphicsLayoutItem::setParentLayoutItem (this=0x5453320, parent=0x0) at graphicsview/qgraphicslayoutitem.cpp:856
#7  0x00007f48b2c8bbd4 in QGraphicsGridLayout::removeAt (this=0x5521f20, index=<optimized out>) at graphicsview/qgraphicsgridlayout.cpp:583
#8  0x00007f4896b75bb3 in SystemTray::TaskArea::relayoutHiddenTasks (this=0x5566f20) at ../../../../../plasma/generic/applets/systemtray/ui/taskarea.cpp:422
#9  0x00007f4896b760cc in SystemTray::TaskArea::qt_metacall (this=0x5566f20, _c=QMetaObject::InvokeMetaMethod, _id=<optimized out>, _a=0x7fff53b9e9f0) at ./taskarea.moc:93
#10 0x00007f48b3338eba in QMetaObject::activate (sender=0x5567000, m=<optimized out>, local_signal_index=<optimized out>, argv=0x0) at kernel/qobject.cpp:3278
#11 0x00007f48b333c789 in QObject::event (this=0x5567000, e=<optimized out>) at kernel/qobject.cpp:1181
#12 0x00007f48b26d6424 in notify_helper (e=0x7fff53b9ef50, receiver=0x5567000, this=0x224c610) at kernel/qapplication.cpp:4486
#13 QApplicationPrivate::notify_helper (this=0x224c610, receiver=0x5567000, e=0x7fff53b9ef50) at kernel/qapplication.cpp:4458
#14 0x00007f48b26db291 in QApplication::notify (this=0x222b700, receiver=0x5567000, e=0x7fff53b9ef50) at kernel/qapplication.cpp:4365
#15 0x00007f48b3fd4126 in KApplication::notify (this=0x222b700, receiver=0x5567000, event=0x7fff53b9ef50) at ../../kdeui/kernel/kapplication.cpp:311
#16 0x00007f48b3325afc in QCoreApplication::notifyInternal (this=0x222b700, receiver=0x5567000, event=0x7fff53b9ef50) at kernel/qcoreapplication.cpp:787
#17 0x00007f48b3352d62 in sendEvent (event=0x7fff53b9ef50, receiver=<optimized out>) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:215
#18 QTimerInfoList::activateTimers (this=0x2248270) at kernel/qeventdispatcher_unix.cpp:603
#19 0x00007f48b3350514 in timerSourceDispatch (source=<optimized out>) at kernel/qeventdispatcher_glib.cpp:184
#20 0x00007f48aa6e9a5d in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#21 0x00007f48aa6ea258 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#22 0x00007f48aa6ea429 in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#23 0x00007f48b3350ed6 in QEventDispatcherGlib::processEvents (this=0x218df40, flags=<optimized out>) at kernel/qeventdispatcher_glib.cpp:422
#24 0x00007f48b277e07e in QGuiEventDispatcherGlib::processEvents (this=<optimized out>, flags=<optimized out>) at kernel/qguieventdispatcher_glib.cpp:204
#25 0x00007f48b3324cf2 in QEventLoop::processEvents (this=<optimized out>, flags=...) at kernel/qeventloop.cpp:149
#26 0x00007f48b3324ef7 in QEventLoop::exec (this=0x7fff53b9f1e0, flags=...) at kernel/qeventloop.cpp:201
#27 0x00007f48b3329789 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1064
#28 0x00007f48b646a1a3 in kdemain (argc=1, argv=0x7fff53b9f5c8) at ../../../../plasma/desktop/shell/main.cpp:120
#29 0x00007f48b60ab30d in __libc_start_main (main=0x400640 <main(int, char**)>, argc=1, ubp_av=0x7fff53b9f5c8, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fff53b9f5b8) at libc-start.c:226
#30 0x0000000000400671 in _start ()

Possible duplicates by query: bug 290465, bug 289385, bug 288804, bug 288096, bug 287387.

Reported using DrKonqi