Application that crashed: plasma-desktop
Version of the application: 0.3
KDE Version: 4.3.2 (KDE 4.3.2)
Qt Version: 4.5.2
Operating System: Linux 2.6.31-16-generic i686
Distribution: Ubuntu 9.10

What I was doing when the application crashed:
this happens regularly with 2 users logged in. the background user has the screen locked, with Firefox still running.
Plasma crashes with no apparent reason, no specific message, just snaps away and restarts.

 -- Backtrace:
Application: Plasma-werkgebied (kdeinit4), signal: Segmentation fault
[Current thread is 1 (Thread 0xb7753700 (LWP 3343))]

Thread 2 (Thread 0xac4c2b70 (LWP 3344)):
#0  0x00d5a422 in __kernel_vsyscall ()
#1  0x4daafe15 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/tls/i686/cmov/libpthread.so.0
#2  0x4d57c4c7 in QWaitConditionPrivate::wait (this=<value optimized out>, mutex=<value optimized out>, time=<value optimized out>) at thread/qwaitcondition_unix.cpp:87
#3  QWaitCondition::wait (this=<value optimized out>, mutex=<value optimized out>, time=<value optimized out>) at thread/qwaitcondition_unix.cpp:159
#4  0x4d897502 in QHostInfoAgent::run (this=<value optimized out>) at kernel/qhostinfo.cpp:260
#5  0x4d57b492 in QThreadPrivate::start (arg=<value optimized out>) at thread/qthread_unix.cpp:188
#6  0x4daab80e in start_thread () from /lib/tls/i686/cmov/libpthread.so.0
#7  0x4da267ee in clone () from /lib/tls/i686/cmov/libc.so.6

Thread 1 (Thread 0xb7753700 (LWP 3343)):
[KCrash Handler]
#6  0x4dc4bd57 in XVisualIDFromVisual () from /usr/lib/libX11.so.6
#7  0x4eb366ae in qt_x11_getX11InfoForWindow (xinfo=) at kernel/qwidget_x11.cpp:400
#8  0x4eb3daee in QWidgetPrivate::create_sys (this=<value optimized out>, window=<value optimized out>, initializeWindow=<value optimized out>, destroyOldWindow=<value optimized out>)
    at kernel/qwidget_x11.cpp:545
#9  0x4eafeabc in QWidget::create (this=<value optimized out>, window=<value optimized out>, initializeWindow=<value optimized out>, destroyOldWindow=<value optimized out>) at kernel/qwidget.cpp:1253
#10 0x00bf3c1e in ?? () from /usr/lib/kde4/plasma_applet_systemtray.so
#11 0x00bef3f0 in ?? () from /usr/lib/kde4/plasma_applet_systemtray.so
#12 0x00bef4cb in ?? () from /usr/lib/kde4/plasma_applet_systemtray.so
#13 0x4d6818c3 in QMetaObject::activate (sender=<value optimized out>, from_signal_index=<value optimized out>, to_signal_index=<value optimized out>, argv=<value optimized out>)
    at kernel/qobject.cpp:3113
#14 0x4d682522 in QMetaObject::activate (sender=<value optimized out>, m=<value optimized out>, local_signal_index=<value optimized out>, argv=) at kernel/qobject.cpp:3187
#15 0x4d6869e7 in QSingleShotTimer::timeout (this=) at .moc/release-shared/qtimer.moc:76
#16 0x4d686afc in QSingleShotTimer::timerEvent (this=<value optimized out>) at kernel/qtimer.cpp:298
#17 0x4d67ba1f in QObject::event (this=<value optimized out>, e=<value optimized out>) at kernel/qobject.cpp:1075
#18 0x4eaa7ef4 in QApplicationPrivate::notify_helper (this=<value optimized out>, receiver=<value optimized out>, e=<value optimized out>) at kernel/qapplication.cpp:4056
#19 0x4eaaf61c in QApplication::notify (this=<value optimized out>, receiver=<value optimized out>, e=<value optimized out>) at kernel/qapplication.cpp:3603
#20 0x4f50963a in KApplication::notify (this=<value optimized out>, receiver=<value optimized out>, event=<value optimized out>) at ../../kdeui/kernel/kapplication.cpp:302
#21 0x4d66bd2b in QCoreApplication::notifyInternal (this=<value optimized out>, receiver=<value optimized out>, event=<value optimized out>) at kernel/qcoreapplication.cpp:610
#22 0x4d698e2e in QCoreApplication::sendEvent (this=<value optimized out>) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:213
#23 QTimerInfoList::activateTimers (this=<value optimized out>) at kernel/qeventdispatcher_unix.cpp:572
#24 0x4d696740 in timerSourceDispatch (source=) at kernel/qeventdispatcher_glib.cpp:165
#25 0x4db77e78 in g_main_dispatch (context=<value optimized out>) at /build/buildd/glib2.0-2.22.2/glib/gmain.c:1960
#26 IA__g_main_context_dispatch (context=<value optimized out>) at /build/buildd/glib2.0-2.22.2/glib/gmain.c:2513
#27 0x4db7b720 in g_main_context_iterate (context=<value optimized out>, block=<value optimized out>, dispatch=<value optimized out>, self=) at /build/buildd/glib2.0-2.22.2/glib/gmain.c:2591
#28 0x4db7b853 in IA__g_main_context_iteration (context=<value optimized out>, may_block=<value optimized out>) at /build/buildd/glib2.0-2.22.2/glib/gmain.c:2654
#29 0x4d69668c in QEventDispatcherGlib::processEvents (this=<value optimized out>, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:327
#30 0x4eb48b85 in QGuiEventDispatcherGlib::processEvents (this=) at kernel/qguieventdispatcher_glib.cpp:202
#31 0x4d66a2d9 in QEventLoop::processEvents (this=<value optimized out>, flags=<value optimized out>) at kernel/qeventloop.cpp:149
#32 0x4d66a72a in QEventLoop::exec (this=<value optimized out>, flags=<value optimized out>) at kernel/qeventloop.cpp:201
#33 0x4d66cb9f in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#34 0x4eaa7d77 in QApplication::exec () at kernel/qapplication.cpp:3525
#35 0x00e0180d in kdemain () from /usr/lib/libkdeinit4_plasma-desktop.so
#36 0x0804dde1 in launch (argc=<value optimized out>, _name=<value optimized out>, args=<value optimized out>, cwd=0x0, envc=0, envs=0x8718680 "", reset_env=false, tty=0x0, avoid_loops=false, 
    startup_id_str=0x80511a5 "0") at ../../kinit/kinit.cpp:677
#37 0x0804ea35 in handle_launcher_request (sock=<value optimized out>, who=<value optimized out>) at ../../kinit/kinit.cpp:1169
#38 0x0804eeac in handle_requests (waitForPid=<value optimized out>) at ../../kinit/kinit.cpp:1362
#39 0x0804fbaf in main (argc=2, argv=0xbfa96f94, envp=0xbfa96fa0) at ../../kinit/kinit.cpp:1793

This bug may be a duplicate of or related to bug 217662

Reported using DrKonqi