Application that crashed: korganizer
Version of the application: 4.3.0
KDE Version: 4.3.00 (KDE 4.3.0)
Qt Version: 4.5.2
Operating System: Linux 2.6.30 i686
Distribution: Debian GNU/Linux unstable (sid)

What I was doing when the application crashed:
1. Open local ics file by clicking on it
2. Dialog opens (I have to select import it, merge or open as separate)
3. I select import
4. Open an event in the calendar 
5. Deselect calendar (note: event of this calendar was still open)
6. Remove calendar (note: event of this calendar was still open)
7. Korganizer crashed

I repeated those steps but second time didn't crashed. Hope you find something useful in the backtrace, if not don't worry about closing it.

 -- Backtrace:
Application: KOrganizer (korganizer), signal: Segmentation fault
[KCrash Handler]
#6  0x08d0ec2e in ?? ()
#7  0xb78bbf61 in KOrg::MonthView::reloadIncidences (this=0x84fb1f8) at ../../korganizer/views/monthview/monthview.cpp:325
#8  0xb78bd250 in KOrg::MonthView::setStartDate (this=0x84fb1f8, start=...) at ../../korganizer/views/monthview/monthview.cpp:291
#9  0xb78bd2be in KOrg::MonthView::showDates (this=0x84fb1f8, start=..., end=...) at ../../korganizer/views/monthview/monthview.cpp:278
#10 0xb790615a in KOViewManager::updateView (this=0x815c710, start=..., end=...) at ../../korganizer/koviewmanager.cpp:215
#11 0xb78f48b7 in CalendarView::updateView (this=0x8155c08, start=..., end=..., updateTodos=true) at ../../korganizer/calendarview.cpp:801
#12 0xb78f653d in CalendarView::updateView (this=0x8155c08) at ../../korganizer/calendarview.cpp:810
#13 0xb78f4070 in CalendarView::resourcesChanged (this=0x8155c08) at ../../korganizer/calendarview.cpp:2528
#14 0xb79043ea in CalendarView::qt_metacall (this=0x8155c08, _c=QMetaObject::InvokeMetaMethod, _id=174, _a=0xbf9f8c08) at ./calendarview.moc:571
#15 0xb7472ad3 in QMetaObject::activate (sender=0x853ecb8, from_signal_index=27, to_signal_index=27, argv=0x0) at kernel/qobject.cpp:3112
#16 0xb7473722 in QMetaObject::activate (sender=0x853ecb8, m=0xb79d5e4c, local_signal_index=0, argv=0x0) at kernel/qobject.cpp:3186
#17 0xb7979417 in ResourceView::resourcesChanged (this=0x853ecb8) at ./resourceview.moc:133
#18 0xb797b2c9 in ResourceView::removeResource (this=0x853ecb8) at ../../korganizer/resourceview.cpp:564
#19 0xb797ef15 in ResourceView::qt_metacall (this=0x853ecb8, _c=QMetaObject::InvokeMetaMethod, _id=5, _a=0xbf9f8e0c) at ./resourceview.moc:107
#20 0xb7472ad3 in QMetaObject::activate (sender=0x854bbf8, from_signal_index=29, to_signal_index=30, argv=0xbf9f8e0c) at kernel/qobject.cpp:3112
#21 0xb7472f00 in QMetaObject::activate (sender=0x854bbf8, m=0xb7306924, from_local_signal_index=2, to_local_signal_index=3, argv=0xbf9f8e0c) at kernel/qobject.cpp:3206
#22 0xb711f951 in QAbstractButton::clicked (this=0x854bbf8, _t1=false) at .moc/release-shared/moc_qabstractbutton.cpp:200
#23 0xb6e4b329 in QAbstractButtonPrivate::emitClicked (this=0x85518b0) at widgets/qabstractbutton.cpp:543
#24 0xb6e4cf14 in QAbstractButtonPrivate::click (this=0x85518b0) at widgets/qabstractbutton.cpp:536
#25 0xb6e4d1a6 in QAbstractButton::mouseReleaseEvent (this=0x854bbf8, e=0xbf9f94cc) at widgets/qabstractbutton.cpp:1115
#26 0xb6f32e8c in QToolButton::mouseReleaseEvent (this=0x854bbf8, e=0xbf9f94cc) at widgets/qtoolbutton.cpp:709
#27 0xb6af373b in QWidget::event (this=0x854bbf8, event=0xbf9f94cc) at kernel/qwidget.cpp:7549
#28 0xb6e4b1ce in QAbstractButton::event (this=0x854bbf8, e=0xbf9f94cc) at widgets/qabstractbutton.cpp:1077
#29 0xb6f3583a in QToolButton::event (this=0x854bbf8, event=0xbf9f94cc) at widgets/qtoolbutton.cpp:1151
#30 0xb6a9d7d4 in QApplicationPrivate::notify_helper (this=0x80751f8, receiver=0x854bbf8, e=0xbf9f94cc) at kernel/qapplication.cpp:4056
#31 0xb6aa62a1 in QApplication::notify (this=0xbf9fad2c, receiver=0x854bbf8, e=0xbf9f94cc) at kernel/qapplication.cpp:3758
#32 0xb7dfe00d in KApplication::notify (this=0xbf9fad2c, receiver=0x854bbf8, event=0xbf9f94cc) at ../../kdeui/kernel/kapplication.cpp:302
#33 0xb745d96b in QCoreApplication::notifyInternal (this=0xbf9fad2c, receiver=0x854bbf8, event=0xbf9f94cc) at kernel/qcoreapplication.cpp:610
#34 0xb6aa532e in QCoreApplication::sendSpontaneousEvent (receiver=0x854bbf8, event=0xbf9f94cc, alienWidget=0x854bbf8, nativeWidget=0x8156b98, buttonDown=0xb7313aa0, lastMouseReceiver=...)
    at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:216
#35 QApplicationPrivate::sendMouseEvent (receiver=0x854bbf8, event=0xbf9f94cc, alienWidget=0x854bbf8, nativeWidget=0x8156b98, buttonDown=0xb7313aa0, lastMouseReceiver=...)
    at kernel/qapplication.cpp:2924
#36 0xb6b13e55 in QETWidget::translateMouseEvent (this=0x8156b98, event=0xbf9faa7c) at kernel/qapplication_x11.cpp:4409
#37 0xb6b13336 in QApplication::x11ProcessEvent (this=0xbf9fad2c, event=0xbf9faa7c) at kernel/qapplication_x11.cpp:3428
#38 0xb6b3d842 in x11EventSourceDispatch (s=0x8077280, callback=0, user_data=0x0) at kernel/qguieventdispatcher_glib.cpp:146
#39 0xb551b368 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#40 0xb551e8c3 in ?? () from /usr/lib/libglib-2.0.so.0
#41 0xb551ea48 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#42 0xb74887f8 in QEventDispatcherGlib::processEvents (this=0x80558d0, flags=...) at kernel/qeventdispatcher_glib.cpp:327
#43 0xb6b3cf85 in QGuiEventDispatcherGlib::processEvents (this=0x80558d0, flags=...) at kernel/qguieventdispatcher_glib.cpp:202
#44 0xb745bfba in QEventLoop::processEvents (this=0xbf9face0, flags=...) at kernel/qeventloop.cpp:149
#45 0xb745c402 in QEventLoop::exec (this=0xbf9face0, flags=...) at kernel/qeventloop.cpp:201
#46 0xb745e859 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#47 0xb6a9d657 in QApplication::exec () at kernel/qapplication.cpp:3525
#48 0x0804eb54 in main (argc=147906960, argv=0x8ce4790) at ../../korganizer/main.cpp:61

Reported using DrKonqi