Version:           unspecified (using KDE 4.5.85) 
OS:                Linux

I was doing completely unrelated stuff when the activity manager crashed. I am pasting a backtrace:

Application: kactivitymanagerd (1.0)
KDE Platform Version: 4.5.85 (4.6 Beta2)
Qt Version: 4.7.1
Operating System: Linux 2.6.34.7-0.5-default i686
Distribution: "openSUSE 11.3 (i586)"

-- Backtrace:
Application: KDE Activity Manager (kactivitymanagerd), signal: Segmentation fault
[KCrash Handler]
#7  QMutex::lock (this=0x80e0d44) at thread/qmutex.cpp:151
#8  0xb5995488 in QMutexLocker (this=0x8197a08, __in_chrg=<value optimized out>) at /usr/include/QtCore/qmutex.h:102
#9  Soprano::Client::SocketHandler::~SocketHandler (this=0x8197a08, __in_chrg=<value optimized out>) at /usr/src/debug/soprano-2.5.63/client/clientconnection.cpp:58
#10 0xb5995632 in Soprano::Client::SocketHandler::~SocketHandler (this=0x8197a08, __in_chrg=<value optimized out>) at /usr/src/debug/soprano-2.5.63/client/clientconnection.cpp:61
#11 0xb5998143 in QThreadStorage<Soprano::Client::SocketHandler*>::deleteData (x=0x8197a08) at /usr/include/QtCore/qthreadstorage.h:133
#12 0xb6d0c4d3 in QThreadStorageData::set (this=0x8199eb0, p=0x8198a98) at thread/qthreadstorage.cpp:148
#13 0xb5995b78 in qThreadStorage_setLocalData<Soprano::Client::SocketHandler> (this=0x81984e0) at /usr/include/QtCore/qthreadstorage.h:92
#14 setLocalData (this=0x81984e0) at /usr/include/QtCore/qthreadstorage.h:148
#15 Soprano::Client::ClientConnection::socketForCurrentThread (this=0x81984e0) at /usr/src/debug/soprano-2.5.63/client/clientconnection.cpp:95
#16 0xb5995c2f in Soprano::Client::ClientConnection::connectInCurrentThread (this=0x81984e0) at /usr/src/debug/soprano-2.5.63/client/clientconnection.cpp:754
#17 0xb5994b03 in Soprano::Client::LocalSocketClient::connect (this=0x8199c24, name=...) at /usr/src/debug/soprano-2.5.63/client/localsocketclient.cpp:141
#18 0xb72b8e68 in init (this=0x8076cd0) at /usr/src/debug/kdelibs-4.5.85/nepomuk/core/nepomukmainmodel.cpp:102
#19 Nepomuk::MainModel::init (this=0x8076cd0) at /usr/src/debug/kdelibs-4.5.85/nepomuk/core/nepomukmainmodel.cpp:176
#20 0xb72b99de in Nepomuk::ResourceManager::init (this=0x807dcf8) at /usr/src/debug/kdelibs-4.5.85/nepomuk/core/resourcemanager.cpp:327
#21 0xb72dd91b in Nepomuk::ResourceManagerPrivate::_k_storageServiceInitialized (this=0x8085538, success=true) at /usr/src/debug/kdelibs-4.5.85/nepomuk/core/resourcemanager.cpp:218
#22 0xb72dda41 in Nepomuk::ResourceManager::qt_metacall (this=0x807dcf8, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0xbffc230c)
    at /usr/src/debug/kdelibs-4.5.85/build/nepomuk/resourcemanager.moc:90
#23 0xb6f68e17 in QDBusConnectionPrivate::deliverCall (this=0x8078fe8, object=0x807dcf8, msg=..., metaTypes=..., slotIdx=135138624) at qdbusintegrator.cpp:919
#24 0xb6f758d6 in QDBusCallDeliveryEvent::placeMetaCall (this=0x81989d0, object=0x807dcf8) at qdbusintegrator_p.h:103
#25 0xb6e22b7f in QObject::event (this=0x807dcf8, e=0x81989d0) at kernel/qobject.cpp:1211
#26 0xb6325414 in QApplicationPrivate::notify_helper (this=0x80909f8, receiver=0x807dcf8, e=0x81989d0) at kernel/qapplication.cpp:4445
#27 0xb632e137 in QApplication::notify (this=0xbffc2b70, receiver=0x807dcf8, e=0x81989d0) at kernel/qapplication.cpp:3845
#28 0xb74937e1 in KApplication::notify (this=0xbffc2b70, receiver=0x807dcf8, event=0x81989d0) at /usr/src/debug/kdelibs-4.5.85/kdeui/kernel/kapplication.cpp:311
#29 0xb6e0d5be in QCoreApplication::notifyInternal (this=0xbffc2b70, receiver=0x807dcf8, event=0x81989d0) at kernel/qcoreapplication.cpp:732
#30 0xb6e1134c in sendEvent (receiver=0x0, event_type=0, data=0x805dca8) at kernel/qcoreapplication.h:215
#31 QCoreApplicationPrivate::sendPostedEvents (receiver=0x0, event_type=0, data=0x805dca8) at kernel/qcoreapplication.cpp:1373
#32 0xb6e1149c in QCoreApplication::sendPostedEvents (receiver=0x0, event_type=0) at kernel/qcoreapplication.cpp:1266
#33 0xb6e3bbd4 in sendPostedEvents (s=0x8087f20) at kernel/qcoreapplication.h:220
#34 postEventSourceDispatch (s=0x8087f20) at kernel/qeventdispatcher_glib.cpp:277
#35 0xb5826b49 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#36 0xb5827350 in ?? () from /usr/lib/libglib-2.0.so.0
#37 0xb582760e in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#38 0xb6e3bd5b in QEventDispatcherGlib::processEvents (this=0x8090ae0, flags=...) at kernel/qeventdispatcher_glib.cpp:422
#39 0xb63db9aa in QGuiEventDispatcherGlib::processEvents (this=0x8090ae0, flags=...) at kernel/qguieventdispatcher_glib.cpp:204
#40 0xb6e0c89d in QEventLoop::processEvents (this=0xbffc2ad4, flags=...) at kernel/qeventloop.cpp:149
#41 0xb6e0cac9 in QEventLoop::exec (this=0xbffc2ad4, flags=...) at kernel/qeventloop.cpp:201
#42 0xb6e11570 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1009
#43 0xb6323114 in QApplication::exec () at kernel/qapplication.cpp:3719
#44 0x0805440f in main (argc=) at /usr/src/debug/kdebase-runtime-4.5.85/activitymanager/main.cpp:40

Report to https://bugs.kde.org

Reproducible: Didn't try