Application that crashed: kontact
Version of the application: 4.3.0 pre
KDE Version: 4.2.90 (KDE 4.2.90 (KDE 4.3 Beta2))
Qt Version: 4.5.0
Operating System: Linux 2.6.28-11-generic x86_64
Distribution: Ubuntu 9.04

What I was doing when the application crashed:
Kontact crashes every time after closing it since I upgraded to Kubuntu 9.04. Sometimes it doesn't crash but consumes 100% cpu time of one core. It seems that the crashes don't have a negative side effect like data loss.

 -- Backtrace:
Application: Kontact (kontact), signal: Segmentation fault
[KCrash Handler]
#5  KCal::Incidence::removeRelation (this=0x2380270, incidence=0x233d410) at /usr/include/qt4/QtCore/qlist.h:667
#6  0x00007fdd6eec1127 in ~Incidence (this=0x233d410) at /build/buildd/kdepimlibs-4.2.90/kcal/incidence.cpp:205
#7  0x00007fdd6eec39e5 in ~Todo (this=0x233d410) at /build/buildd/kdepimlibs-4.2.90/kcal/todo.cpp:103
#8  0x00007fdd6eee8b6e in KCal::CalendarLocal::close (this=0x1bb5430) at /usr/include/qt4/QtCore/qalgorithms.h:350
#9  0x00007fdd6e9c0336 in KRES::Resource::close (this=0x1b961c0) at /build/buildd/kdepimlibs-4.2.90/kresources/resource.cpp:141
#10 0x00007fdd6ef3f659 in KCal::CalendarResources::close (this=0x1b85460) at /build/buildd/kdepimlibs-4.2.90/kcal/calendarresources.cpp:352
#11 0x00007fdd6ef3f9dd in ~CalendarResources (this=0x2380270) at /build/buildd/kdepimlibs-4.2.90/kcal/calendarresources.cpp:249
#12 0x00007fdd5ade3eb6 in ~StdCalendar (this=0x2380270) at /build/buildd/kdepim-4.2.90/korganizer/stdcalendar.cpp:112
#13 0x00007fdd5ade5557 in K3StaticDeleter<KOrg::StdCalendar>::destructObject (this=0x7fdd5afe71e0) at /usr/include/k3staticdeleter.h:174
#14 0x00007fdd7016a70c in K3StaticDeleterPrivate::deleteStaticDeleters () at /build/buildd/kde4libs-4.2.90/kde3support/kdecore/k3staticdeleter.cpp:56
#15 0x00007fdd6b431ce5 in qt_call_post_routines () at kernel/qcoreapplication.cpp:163
#16 0x00007fdd6bff3c48 in ~QApplication (this=0x7fff78f6c170) at kernel/qapplication.cpp:985
#17 0x00000000004049d1 in main (argc=1, argv=0x7fff78f6c858) at /build/buildd/kdepim-4.2.90/kontact/src/main.cpp:67

Reported using DrKonqi