Application that crashed: kontact
Version of the application: 4.3.2
KDE Version: 4.3.2 (KDE 4.3.2)
Qt Version: 4.5.2
Operating System: Linux 2.6.28-16-generic i686
Distribution: Ubuntu 9.04

What I was doing when the application crashed:
I closed the application because it was not finishing a transaction wit an IMAP folder (no progress at all). When I restarted KMail, it crashed at once. 

 -- Backtrace:
Application: Kontact (kontact), signal: Segmentation fault
[KCrash Handler]
#6  Kontact::MainWindow::activatePluginModule (this=0x8f36100) at /build/buildd/kdepim-4.3.2/kontact/src/mainwindow.cpp:303
#7  0xb78f00a4 in Kontact::MainWindow::setActivePluginModule (this=0x8f36100, module=@0xbf998644) at /build/buildd/kdepim-4.3.2/kontact/src/mainwindow.cpp:281
#8  0x0804ac57 in KontactApp::newInstance (this=0xbf9991a8) at /build/buildd/kdepim-4.3.2/kontact/src/main.cpp:147
#9  0xb6d8bb06 in KUniqueApplicationAdaptor::newInstance (this=0x8faa540, asn_id=@0x90153e8, args=@0x9016c28) at /build/buildd/kde4libs-4.3.2/kdeui/kernel/kuniqueapplication.cpp:459
#10 0xb6d8bbae in KUniqueApplicationAdaptor::qt_metacall (this=0x8faa540, _c=QMetaObject::InvokeMetaMethod, _id=0, _a=0xbf998898)
    at /build/buildd/kde4libs-4.3.2/obj-i486-linux-gnu/kdeui/kuniqueapplication_p.moc:75
#11 0xb5ddee5a in QDBusConnectionPrivate::deliverCall (this=0x8f26f48, object=0x8faa540, msg=@0x95175e8, metaTypes=@0x8fc2bb4, slotIdx=4) at qdbusintegrator.cpp:891
#12 0xb5de0179 in QDBusConnectionPrivate::activateCall (this=0x8f26f48, object=0x8faa540, flags=337, msg=@0x95175e8) at qdbusintegrator.cpp:803
#13 0xb5de05e1 in QDBusConnectionPrivate::activateObject (this=0x8f26f48, node=@0x95175d4, msg=@0x95175e8, pathStartPos=16) at qdbusintegrator.cpp:1370
#14 0xb5de0ada in QDBusActivateObjectEvent::placeMetaCall (this=0x95175a8) at qdbusintegrator.cpp:1464
#15 0xb5cd73b0 in QObject::event (this=0xbf9991a8, e=0x95175a8) at kernel/qobject.cpp:1111
#16 0xb5cc656b in QCoreApplication::event (this=0xbf9991a8, e=0x95175a8) at kernel/qcoreapplication.cpp:1434
#17 0xb6190679 in QApplication::event (this=0xbf9991a8, e=0x95175a8) at kernel/qapplication.cpp:2317
#18 0xb618ad3c in QApplicationPrivate::notify_helper (this=0x8f36b98, receiver=0xbf9991a8, e=0x95175a8) at kernel/qapplication.cpp:4056
#19 0xb619303e in QApplication::notify (this=0xbf9991a8, receiver=0xbf9991a8, e=0x95175a8) at kernel/qapplication.cpp:3603
#20 0xb6d8449d in KApplication::notify (this=0xbf9991a8, receiver=0xbf9991a8, event=0x95175a8) at /build/buildd/kde4libs-4.3.2/kdeui/kernel/kapplication.cpp:302
#21 0xb5cc6bcb in QCoreApplication::notifyInternal (this=0xbf9991a8, receiver=0xbf9991a8, event=0x95175a8) at kernel/qcoreapplication.cpp:610
#22 0xb5cc7825 in QCoreApplicationPrivate::sendPostedEvents (receiver=0x0, event_type=0, data=0x8f0f440) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:213
#23 0xb5cc7a1d in QCoreApplication::sendPostedEvents (receiver=0x0, event_type=0) at kernel/qcoreapplication.cpp:1140
#24 0xb5cf26af in postEventSourceDispatch (s=0x8f2f998) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:218
#25 0xb4d97b88 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#26 0xb4d9b0eb in ?? () from /usr/lib/libglib-2.0.so.0
#27 0xb4d9b268 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#28 0xb5cf22f8 in QEventDispatcherGlib::processEvents (this=0x8f0f028, flags={i = -1080455048}) at kernel/qeventdispatcher_glib.cpp:327
#29 0xb622ca75 in QGuiEventDispatcherGlib::processEvents (this=0x8f0f028, flags={i = -1080455000}) at kernel/qguieventdispatcher_glib.cpp:202
#30 0xb5cc51fa in QEventLoop::processEvents (this=0xbf999120, flags={i = -1080454936}) at kernel/qeventloop.cpp:149
#31 0xb5cc5642 in QEventLoop::exec (this=0xbf999120, flags={i = -1080454872}) at kernel/qeventloop.cpp:201
#32 0xb5cc7ae9 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#33 0xb618abb7 in QApplication::exec () at kernel/qapplication.cpp:3525
#34 0x0804bfef in main (argc=1, argv=0xbf9994a4) at /build/buildd/kdepim-4.3.2/kontact/src/main.cpp:218

Reported using DrKonqi