Version:           r930811 (using 4.2.2 (KDE 4.2.2), Kubuntu packages)
Compiler:          cc
OS:                Linux (x86_64) release 2.6.28-11-generic

This bug was originally reported in launchpad as
  https://bugs.launchpad.net/bugs/362864
It might be the same as bug 189691 but with a complete stacktrace
  https://bugs.kde.org/show_bug.cgi?id=189691
Full gdb output was pasted here
  http://kde.pastey.net/112474

Plasma crashes all the time (and restarts), it seems to be triggered by the network-manager widget/plasmoid being confused by disappearing and appearing WLAN networks.

The plasmoid was put on the workspace with an Internal Extender Container (whatever that is).

The stacktrace doesn't make much sense, QDBusAbstractInterface::isValid crashes when it tries to access the d-pointer (I think). Anyway, here it is for you pleasure:

  #0  0x00007fa2c0acbc44 in QDBusAbstractInterface::isValid (this=0x2878370) at qdbusabstractinterface.cpp:301  
  #1  0x00007fa2a64eddf2 in ConnectionList::assessConnections (this=0x285cb50, service=0x2878370)  
      at /build/buildd/plasma-widget-network-manager-0.0+svn930811/applet/connectionlist.cpp:70  
  #2  0x00007fa2a64ee73e in ConnectionList::reassess (this=0x285cb50)  
      at /build/buildd/plasma-widget-network-manager-0.0+svn930811/applet/connectionlist.cpp:170  
  #3  0x00007fa2a64ebd70 in InterfaceGroup::qt_metacall (this=0x285cb50, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>,  
      _a=0x7fffcd363450) at /build/buildd/plasma-widget-network-manager-0.0+svn930811/obj-x86_64-linux-gnu/applet/moc_interfacegroup.cpp:89  
  #4  0x00007fa2c07b71f2 in QMetaObject::activate (sender=0x28678e0, from_signal_index=<value optimized out>, to_signal_index=5, argv=0x0)  
      at kernel/qobject.cpp:3069  
  #5  0x00007fa2a64eadc5 in AbstractWirelessEnvironment::networkDisappeared (this=0x2878370, _t1=<value optimized out>)  
      at /build/buildd/plasma-widget-network-manager-0.0+svn930811/obj-x86_64-linux-gnu/applet/moc_wirelessenvironment.cpp:89  
  #6  0x00007fa2a64eb664 in WirelessEnvironmentMerged::qt_metacall (this=0x28678e0, _c=QMetaObject::InvokeMetaMethod,  
      _id=<value optimized out>, _a=0x7fffcd363570)  
      at /build/buildd/plasma-widget-network-manager-0.0+svn930811/obj-x86_64-linux-gnu/applet/moc_mergedwireless.cpp:138  
  #7  0x00007fa2c07b71f2 in QMetaObject::activate (sender=0x28a6aa0, from_signal_index=<value optimized out>, to_signal_index=5, argv=0x0)  
      at kernel/qobject.cpp:3069  
  #8  0x00007fa2a64eaeb5 in AbstractWirelessNetwork::noAccessPoints (this=0x2878370, _t1=<value optimized out>)  
      at /build/buildd/plasma-widget-network-manager-0.0+svn930811/obj-x86_64-linux-gnu/applet/moc_wirelessnetwork.cpp:89  
  #9  0x00007fa2a64efefb in WirelessNetworkMerged::disappeared (this=0x28a6aa0, ssid=@0x28a6d50)  
      at /build/buildd/plasma-widget-network-manager-0.0+svn930811/applet/mergedwireless.cpp:111  
  #10 0x00007fa2a64eb70e in WirelessNetworkMerged::qt_metacall (this=0x28a6aa0, _c=QMetaObject::InvokeMetaMethod, _id=97, _a=0x7fffcd363700)  
      at /build/buildd/plasma-widget-network-manager-0.0+svn930811/obj-x86_64-linux-gnu/applet/moc_mergedwireless.cpp:70  
  #11 0x00007fa2c07b71f2 in QMetaObject::activate (sender=0x2859f80, from_signal_index=<value optimized out>, to_signal_index=5, argv=0x0)  
      at kernel/qobject.cpp:3069  
  #12 0x00007fa2a64eadc5 in AbstractWirelessEnvironment::networkDisappeared (this=0x2878370, _t1=<value optimized out>)  
      at /build/buildd/plasma-widget-network-manager-0.0+svn930811/obj-x86_64-linux-gnu/applet/moc_wirelessenvironment.cpp:89  
  #13 0x00007fa2a650ad10 in WirelessEnvironment::removeNetwork (this=0x2859f80, ssid=@0x28a6d50)  
      at /build/buildd/plasma-widget-network-manager-0.0+svn930811/applet/wirelessenvironment.cpp:137  
  #14 0x00007fa2a64eb03d in WirelessEnvironment::qt_metacall (this=0x2859f80, _c=QMetaObject::InvokeMetaMethod, _id=97, _a=0x7fffcd363860)  
      at /build/buildd/plasma-widget-network-manager-0.0+svn930811/obj-x86_64-linux-gnu/applet/moc_wirelessenvironment.cpp:142  
  #15 0x00007fa2c07b71f2 in QMetaObject::activate (sender=0x28528a0, from_signal_index=<value optimized out>, to_signal_index=5, argv=0x0)  
      at kernel/qobject.cpp:3069  
  #16 0x00007fa2a64eaeb5 in AbstractWirelessNetwork::noAccessPoints (this=0x2878370, _t1=<value optimized out>)  
      at /build/buildd/plasma-widget-network-manager-0.0+svn930811/obj-x86_64-linux-gnu/applet/moc_wirelessnetwork.cpp:89  
  #17 0x00007fa2a64ebae4 in WirelessNetwork::qt_metacall (this=0x28528a0, _c=QMetaObject::InvokeMetaMethod, _id=97, _a=0x7fffcd363980)  
      at /build/buildd/plasma-widget-network-manager-0.0+svn930811/obj-x86_64-linux-gnu/applet/moc_wirelessnetwork.cpp:143  
  #18 0x00007fa2c07b71f2 in QMetaObject::activate (sender=0x28502e0, from_signal_index=<value optimized out>, to_signal_index=11, argv=0x0)  
      at kernel/qobject.cpp:3069  
  #19 0x00007fa2a982acc5 in Solid::Control::WirelessNetworkInterface::accessPointDisappeared (this=0x2878370, _t1=<value optimized out>)  
      at /build/buildd/kdebase-workspace-4.2.2/obj-x86_64-linux-gnu/libs/solid/control/wirelessnetworkinterface.moc:151  
  #20 0x00007fa2a982c17c in Solid::Control::WirelessNetworkInterface::qt_metacall (this=0x28502e0, _c=QMetaObject::InvokeMetaMethod,  
      _id=<value optimized out>, _a=0x7fffcd363aa0)  
  ---Type <return> to continue, or q <return> to quit---  
      at /build/buildd/kdebase-workspace-4.2.2/obj-x86_64-linux-gnu/libs/solid/control/wirelessnetworkinterface.moc:110  
  #21 0x00007fa2c07b71f2 in QMetaObject::activate (sender=0x2978f00, from_signal_index=<value optimized out>, to_signal_index=11, argv=0x0)  
      at kernel/qobject.cpp:3069  
  #22 0x00007fa2a60a4705 in NMWirelessNetworkInterface::accessPointDisappeared (this=0x2878370, _t1=<value optimized out>)  
      at /build/buildd/kdebase-workspace-4.2.2/obj-x86_64-linux-gnu/solid/networkmanager-0.7/moc_wirelessnetworkinterface.cpp:134  
  #23 0x00007fa2a60b2011 in NMWirelessNetworkInterface::accessPointRemoved (this=0x2978f00, apPath=@0x3600ef0)  
      at /build/buildd/kdebase-workspace-4.2.2/solid/networkmanager-0.7/wirelessnetworkinterface.cpp:187  
  #24 0x00007fa2a60a48b4 in NMWirelessNetworkInterface::qt_metacall (this=0x2978f00, _c=QMetaObject::InvokeMetaMethod,  
      _id=<value optimized out>, _a=0x7fffcd363cb0)  
      at /build/buildd/kdebase-workspace-4.2.2/obj-x86_64-linux-gnu/solid/networkmanager-0.7/moc_wirelessnetworkinterface.cpp:94  
  #25 0x00007fa2c07b71f2 in QMetaObject::activate (sender=0x2979238, from_signal_index=<value optimized out>, to_signal_index=6, argv=0x0)  
      at kernel/qobject.cpp:3069  
  #26 0x00007fa2a60b9285 in OrgFreedesktopNetworkManagerDeviceWirelessInterface::AccessPointRemoved (this=0x2878370, _t1=<value optimized out>)  
      at /build/buildd/kdebase-workspace-4.2.2/obj-x86_64-linux-gnu/solid/networkmanager-0.7/nm-device-wifiinterface.moc:135  
  #27 0x00007fa2a60b977c in OrgFreedesktopNetworkManagerDeviceWirelessInterface::qt_metacall (this=0x2979238, _c=QMetaObject::InvokeMetaMethod,  
      _id=97, _a=0x7fffcd3640b0)  
      at /build/buildd/kdebase-workspace-4.2.2/obj-x86_64-linux-gnu/solid/networkmanager-0.7/nm-device-wifiinterface.moc:86  
  #28 0x00007fa2c0abff83 in QDBusConnectionPrivate::deliverCall (this=0x26ecbd0, object=0x2979238, msg=@0x35ffec8, metaTypes=@0x35ffed0,  
      slotIdx=6) at qdbusintegrator.cpp:891  
  #29 0x00007fa2c0ac7d0f in QDBusCallDeliveryEvent::placeMetaCall (this=0x61, object=0x2878370) at qdbusintegrator_p.h:101  
  #30 0x00007fa2c07b1848 in QObject::event (this=0x2979238, e=0x35ffe80) at kernel/qobject.cpp:1118  
  #31 0x00007fa2c0ee683d in QApplicationPrivate::notify_helper (this=0x2391250, receiver=0x2979238, e=0x35ffe80) at kernel/qapplication.cpp:4084  
  #32 0x00007fa2c0eeea2a in QApplication::notify (this=0x2364880, receiver=0x2979238, e=0x35ffe80) at kernel/qapplication.cpp:4049  
  #33 0x00007fa2c35a326b in KApplication::notify (this=0x2364880, receiver=0x2979238, event=0x35ffe80)  
      at /build/buildd/kde4libs-4.2.2/kdeui/kernel/kapplication.cpp:307  
  #34 0x00007fa2c07a175c in QCoreApplication::notifyInternal (this=0x2364880, receiver=0x2979238, event=0x35ffe80)  
      at kernel/qcoreapplication.cpp:602  
  #35 0x00007fa2c07a23ca in QCoreApplicationPrivate::sendPostedEvents (receiver=0x0, event_type=0, data=0x2340a30)  
      at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:213  
  #36 0x00007fa2c07cb1e3 in postEventSourceDispatch (s=<value optimized out>)  
      at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:218  
  #37 0x00007fa2bb3dd20a in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0  
  #38 0x00007fa2bb3e08e0 in ?? () from /usr/lib/libglib-2.0.so.0  
  #39 0x00007fa2bb3e0a7c in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0  
  #40 0x00007fa2c07cae6f in QEventDispatcherGlib::processEvents (this=0x2344ea0, flags=<value optimized out>)  
      at kernel/qeventdispatcher_glib.cpp:323  
  #41 0x00007fa2c0f7ec9f in QGuiEventDispatcherGlib::processEvents (this=0x2878370, flags=<value optimized out>)  
      at kernel/qguieventdispatcher_glib.cpp:202  
  #42 0x00007fa2c07a0002 in QEventLoop::processEvents (this=<value optimized out>, flags={i = -852080128}) at kernel/qeventloop.cpp:149  
  #43 0x00007fa2c07a03cd in QEventLoop::exec (this=0x7fffcd364a40, flags={i = -852080048}) at kernel/qeventloop.cpp:200  
  #44 0x00007fa2c07a2694 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:880  
  #45 0x00007fa2c4f029bb in kdemain (argc=2, argv=0x7fffcd364d48) at /build/buildd/kdebase-workspace-4.2.2/plasma/shells/desktop/main.cpp:54  
  ---Type <return> to continue, or q <return> to quit---  
  #46 0x00007fa2bfb4e5a6 in __libc_start_main (main=0x400890 <main>, argc=2, ubp_av=0x7fffcd364d48, init=0x4008c0 <__libc_csu_init>,  
      fini=<value optimized out>, rtld_fini=<value optimized out>, stack_end=0x7fffcd364d38) at libc-start.c:220  
  #47 0x00000000004007c9 in _start () at ../sysdeps/x86_64/elf/start.S:113