Version:            (using Devel)
Installed from:    Compiled sources
OS:                Linux

Setup:
I ran kontact (kmail) in a recent KDE4 SVN snapshot via a liveCD (http://grundleborg.wordpress.com/2008/05/25/kde-pim-krush-day-is-now/) in a virtual machine. When kontact froze, I killed the process. After that I shut down the KDE4 session. Instead of shutting down, plasma crashed with the backtrace below. (Only konsole was still open at that time)

Application: Plasma Workspace (plasma), signal SIGSEGV
[Thread debugging using libthread_db enabled]
[New Thread 0xb528f940 (LWP 3714)]
[New Thread 0xb3833b90 (LWP 3717)]
[KCrash handler]
#6  0x03000065 in ?? ()
#7  0xb68cea1a in QObject::disconnect (sender=0x9f01698, 
    signal=0x9f4bbf1 "deviceAdded(QString)", receiver=0x9f4caf8, 
    method=0x9f7c4e9 "deviceAdded(QString)")
    at /usr/src/KDE/source/qt-copy/src/corelib/kernel/qobject.cpp:2562
#8  0xb2c8fee4 in SolidDeviceEngine::~SolidDeviceEngine ()
   from /opt/kde4/lib/kde4/plasma_engine_soliddevice.so
#9  0xb7ea6929 in Plasma::DataEngineManager::Private::~Private ()
   from /opt/kde4/lib/libplasma.so.2
#10 0xb7ea5cd4 in Plasma::DataEngineManager::~DataEngineManager ()
   from /opt/kde4/lib/libplasma.so.2
#11 0xb7ea6f8d in Plasma::DataEngineManagerSingleton::~DataEngineManagerSingleton () from /opt/kde4/lib/libplasma.so.2
#12 0xb7ea5d5f in Plasma::._167::destroy () from /opt/kde4/lib/libplasma.so.2
#13 0xb7e61887 in KCleanUpGlobalStatic::~KCleanUpGlobalStatic ()
   from /opt/kde4/lib/libplasma.so.2
#14 0xb7ea5334 in __tcf_0 () from /opt/kde4/lib/libplasma.so.2
#15 0xb5656004 in exit () from /lib/i686/cmov/libc.so.6
#16 0xb65e4391 in _IceDefaultIOErrorHandler () from /usr/lib/libICE.so.6
#17 0xb65ebdb3 in _IceRead () from /usr/lib/libICE.so.6
#18 0xb65f010f in IceProcessMessages () from /usr/lib/libICE.so.6
#19 0xb5b4da72 in QSmSocketReceiver::socketActivated (this=0x9ddac68)
    at /usr/src/KDE/source/qt-copy/src/gui/kernel/qapplication_x11.cpp:5361
#20 0xb5b4dae3 in QSmSocketReceiver::qt_metacall (this=0x9ddac68, 
    _c=QMetaObject::InvokeMetaMethod, _id=0, _a=0xbfdce2bc)
    at .moc/debug-shared/qapplication_x11.moc:64
#21 0xb68d2d75 in QMetaObject::activate (sender=0x9de4710, 
    from_signal_index=4, to_signal_index=4, argv=0xbfdce2bc)
    at /usr/src/KDE/source/qt-copy/src/corelib/kernel/qobject.cpp:3001
#22 0xb68d32ff in QMetaObject::activate (sender=0x9de4710, m=0xb69c6a50, 
    local_signal_index=0, argv=0xbfdce2bc)
    at /usr/src/KDE/source/qt-copy/src/corelib/kernel/qobject.cpp:3071
#23 0xb691d310 in QSocketNotifier::activated (this=0x9de4710, _t1=11)
    at .moc/debug-shared/moc_qsocketnotifier.cpp:81
#24 0xb68dd0ad in QSocketNotifier::event (this=0x9de4710, e=0xbfdce7d8)
    at /usr/src/KDE/source/qt-copy/src/corelib/kernel/qsocketnotifier.cpp:326
#25 0xb5ad5261 in QApplicationPrivate::notify_helper (this=0x9dc0218, 
    receiver=0x9de4710, e=0xbfdce7d8)
    at /usr/src/KDE/source/qt-copy/src/gui/kernel/qapplication.cpp:3772
#26 0xb5ad557a in QApplication::notify (this=0x9dba1c0, receiver=0x9de4710, 
    e=0xbfdce7d8)
    at /usr/src/KDE/source/qt-copy/src/gui/kernel/qapplication.cpp:3366
#27 0xb7a0375b in KApplication::notify () from /opt/kde4/lib/libkdeui.so.5
#28 0xb68bb0e9 in QCoreApplication::notifyInternal (this=0x9dba1c0, 
    receiver=0x9de4710, event=0xbfdce7d8)
    at /usr/src/KDE/source/qt-copy/src/corelib/kernel/qcoreapplication.cpp:587
#29 0xb6ee52fb in QCoreApplication::sendEvent (receiver=0x9de4710, 
    event=0xbfdce7d8)
    at ../../../../include/QtCore/../../../../source/qt-copy/src/corelib/kernel/qcoreapplication.h:215
#30 0xb68f161e in socketNotifierSourceDispatch (source=0x9dc2f68)
    at /usr/src/KDE/source/qt-copy/src/corelib/kernel/qeventdispatcher_glib.cpp:111
#31 0xb53bc978 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#32 0xb53bfbce in ?? () from /usr/lib/libglib-2.0.so.0
#33 0x09dc22d0 in ?? ()
#34 0x00000000 in ?? ()
#0  0xb7fb3422 in __kernel_vsyscall ()