Plasma crashes on shutdown (via kickoff -leave - shutdown) and two kcrash 
windows pop-up - backtraces from both below. Once the two kcrash windows are 
closed, shutdown proceeds normally. I get this about one in five shutdowns. I 
ususally have skype, akregator and network manager in the systray, but all 
other applications closed. I have had the same crash with them all closed 
though, and haven't been able to reliably repeat this. Backtraces below in case 
they are useful. Please let me know if/how I can provide any more information 
Thanks.

Application: Plasma Workspace (<unknown>), signal SIGSEGV
(no debugging symbols found)
Using host libthread_db library "/lib/libthread_db.so.1".
(no debugging symbols found)
[Thread debugging using libthread_db enabled]
[New Thread -1208247680 (LWP 6269)]
[New Thread -1233503344 (LWP 6270)]
[KCrash handler]
#6  0x07301b63 in ?? ()
#7  0x07c4fe74 in QObject::disconnect (sender=0x92ff090, 
    signal=0x9341fc1 "deviceAdded(QString)", receiver=0x92f7c00, 
    method=0x92fbd69 "deviceAdded(QString)") at kernel/qobject.cpp:2571
#8  0x014b74b4 in SolidDeviceEngine::~SolidDeviceEngine$delete ()
   from /home/kde-devel/kde/kde4/lib/kde4/plasma_engine_soliddevice.so
#9  0x001edddb in Plasma::DataEngineManager::~DataEngineManager ()
   from /home/kde-devel/kde/kde4/lib/libplasma.so.1
#10 0x001ee07a in Plasma::._167::destroy ()
   from /home/kde-devel/kde/kde4/lib/libplasma.so.1
#11 0x001ed108 in __tcf_0 () from /home/kde-devel/kde/kde4/lib/libplasma.so.1
#12 0x0113363e in exit () from /lib/libc.so.6
#13 0x008b0fb9 in _IceDefaultIOErrorHandler () from /usr/lib/libICE.so.6
#14 0x008b90a3 in _IceRead () from /usr/lib/libICE.so.6
#15 0x008bd81f in IceProcessMessages () from /usr/lib/libICE.so.6
#16 0x026c7d4c in QSmSocketReceiver::socketActivated (this=0x90b87b0)
    at kernel/qapplication_x11.cpp:5361
#17 0x026c7dbd in QSmSocketReceiver::qt_metacall (this=0x90b87b0, 
    _c=QMetaObject::InvokeMetaMethod, _id=0, _a=0xbffe1d5c)
    at .moc/debug-shared/qapplication_x11.moc:64
#18 0x07c52e61 in QMetaObject::activate (sender=0x90e51a0, 
    from_signal_index=4, to_signal_index=4, argv=0xbffe1d5c)
    at kernel/qobject.cpp:3007
#19 0x07c532e3 in QMetaObject::activate (sender=0x90e51a0, m=0x7cedb10, 
    local_signal_index=0, argv=0xbffe1d5c) at kernel/qobject.cpp:3080
#20 0x07c93240 in QSocketNotifier::activated (this=0x90e51a0, _t1=16)
    at .moc/debug-shared/moc_qsocketnotifier.cpp:81
#21 0x07c5d1ed in QSocketNotifier::event (this=0x90e51a0, e=0xbffe2298)
    at kernel/qsocketnotifier.cpp:326
#22 0x0265ad07 in QApplicationPrivate::notify_helper (this=0x907f6b8, 
    receiver=0x90e51a0, e=0xbffe2298) at kernel/qapplication.cpp:3772
#23 0x0265b020 in QApplication::notify (this=0x90753b0, receiver=0x90e51a0, 
    e=0xbffe2298) at kernel/qapplication.cpp:3366
#24 0x01724977 in KApplication::notify (this=0x90753b0, receiver=0x90e51a0, 
    event=0xbffe2298)
    at /home/kde-devel/kde/src/kdelibs/kdeui/kernel/kapplication.cpp:311
#25 0x07c3ebb2 in QCoreApplication::notifyInternal (this=0x90753b0, 
    receiver=0x90e51a0, event=0xbffe2298) at kernel/qcoreapplication.cpp:583
#26 0x00d8ab6b in QCoreApplication::sendEvent (receiver=0x90e51a0, 
    event=0xbffe2298)
    at 
../../../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:215
#27 0x07c6e3aa in socketNotifierSourceDispatch (source=0x9081928)
    at kernel/qeventdispatcher_glib.cpp:111
#28 0x031e61ac in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#29 0x031e95ef in ?? () from /lib/libglib-2.0.so.0
#30 0x031e9b55 in g_main_context_iteration () from /lib/libglib-2.0.so.0
#31 0x07c6dbe4 in QEventDispatcherGlib::processEvents (this=0x9076170, 
    flags=@0xbffe23e8) at kernel/qeventdispatcher_glib.cpp:325
#32 0x02702db4 in QGuiEventDispatcherGlib::processEvents (this=0x9076170, 
    flags=@0xbffe2418) at kernel/qguieventdispatcher_glib.cpp:204
#33 0x07c3b70e in QEventLoop::processEvents (this=0xbffe2490, 
    flags=@0xbffe2454) at kernel/qeventloop.cpp:149
#34 0x07c3b94d in QEventLoop::exec (this=0xbffe2490, flags=@0xbffe2498)
    at kernel/qeventloop.cpp:196
#35 0x07c3f39b in QCoreApplication::exec () at kernel/qcoreapplication.cpp:845
#36 0x0265aa04 in QApplication::exec () at kernel/qapplication.cpp:3304
#37 0x0011c736 in kdemain ()
   from /home/kde-devel/kde/kde4/lib/libkdeinit4_plasma.so
#38 0x08048802 in main ()
#0  0x00110402 in __kernel_vsyscall ()



Application: Plasma Workspace (plasma), signal SIGSEGV
(no debugging symbols found)
Using host libthread_db library "/lib/libthread_db.so.1".
(no debugging symbols found)
[Thread debugging using libthread_db enabled]
[New Thread -1208694144 (LWP 5943)]
[KCrash handler]
#6  0x022277a6 in XFreePixmap () from /usr/lib/libX11.so.6
#7  0x0772bc31 in TaskManager::Task::~Task$delete ()
   from /home/kde-devel/kde/kde4/lib/libtaskmanager.so.4
#8  0x07732366 in QMap<unsigned long, KSharedPtr<TaskManager::Task> >::freeData 
() from /home/kde-devel/kde/kde4/lib/libtaskmanager.so.4
#9  0x077301d5 in TaskManager::TaskManager::~TaskManager ()
   from /home/kde-devel/kde/kde4/lib/libtaskmanager.so.4
#10 0x0773021a in TaskManager::._237::destroy ()
   from /home/kde-devel/kde/kde4/lib/libtaskmanager.so.4
#11 0x0772f3c8 in __tcf_0 ()
   from /home/kde-devel/kde/kde4/lib/libtaskmanager.so.4
#12 0x0113363e in exit () from /lib/libc.so.6
#13 0x0111d398 in __libc_start_main () from /lib/libc.so.6
#14 0x08048721 in _start ()
#0  0x00110402 in __kernel_vsyscall ()