Application that crashed: kmail
Version of the application: 1.12.0
KDE Version: 4.2.96 (KDE 4.2.96 (KDE 4.3 RC2))
Qt Version: 4.5.1
Operating System: Linux 2.6.27-gentoo-r7 x86_64

What I was doing when the application crashed:
KMail pretty much stops working when I try to read the "LKML" folder apparently due to its size. This seems to also prevent me from even making a sub-folder and restarting.

 -- Backtrace:
Application: KMail (kmail), signal: Segmentation fault
[Current thread is 0 (LWP 22301)]

Thread 2 (Thread 0x7f56bd1e4950 (LWP 22305)):
#0  0x00007f56cc9d003d in pthread_cond_timedwait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
#1  0x00007f56ccc3bd57 in QWaitCondition::wait () from /usr/lib64/qt4/libQtCore.so.4
#2  0x00007f56ccc33161 in ?? () from /usr/lib64/qt4/libQtCore.so.4
#3  0x00007f56ccc3b039 in ?? () from /usr/lib64/qt4/libQtCore.so.4
#4  0x00007f56cc9cc007 in start_thread () from /lib/libpthread.so.0
#5  0x00007f56cbf9b48d in clone () from /lib/libc.so.6
#6  0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7f56d2bbe760 (LWP 22301)):
[KCrash Handler]
#5  0x00007f56ccc40a60 in ?? () from /usr/lib64/qt4/libQtCore.so.4
#6  0x00007f56cccce173 in ?? () from /usr/lib64/qt4/libQtCore.so.4
#7  0x00007f56cccce1f7 in QUrl::toPercentEncoding () from /usr/lib64/qt4/libQtCore.so.4
#8  0x00007f56d1fffad5 in KUrl::prettyUrl (this=0x28c42e8, trailing=KUrl::LeaveTrailingSlash) at /var/tmp/portage/kde-base/kdelibs-4.2.96/work/kdelibs-4.2.96/kdecore/io/kurl.cpp:1045
#9  0x00007f56ce587633 in KIO::JobPrivate::emitTransferring (job=0x295d1b0, url=@0x28c42e8) at /var/tmp/portage/kde-base/kdelibs-4.2.96/work/kdelibs-4.2.96/kio/kio/job.cpp:162
#10 0x00007f56ce587701 in KIO::TransferJobPrivate::start (this=0x28c4250, slave=0x2053620) at /var/tmp/portage/kde-base/kdelibs-4.2.96/work/kdelibs-4.2.96/kio/kio/job.cpp:1130
#11 0x00007f56ce61d4b7 in startJob (job=0x295d1b0, slave=0x2053620) at /var/tmp/portage/kde-base/kdelibs-4.2.96/work/kdelibs-4.2.96/kio/kio/scheduler.cpp:60
#12 0x00007f56ce61dde2 in KIO::SchedulerPrivate::slotScheduleCoSlave (this=0x1945760) at /var/tmp/portage/kde-base/kdelibs-4.2.96/work/kdelibs-4.2.96/kio/kio/scheduler.cpp:918
#13 0x00007f56ce620e07 in KIO::Scheduler::qt_metacall (this=0x174fdc0, _c=QMetaObject::InvokeMetaMethod, _id=10, _a=0x7fffdac0cfe0)
    at /var/tmp/portage/kde-base/kdelibs-4.2.96/work/kdelibs-4.2.96_build/kio/scheduler.moc:106
#14 0x00007f56ccd1f7e5 in QMetaObject::activate () from /usr/lib64/qt4/libQtCore.so.4
#15 0x00007f56ccd1bf13 in QObject::event () from /usr/lib64/qt4/libQtCore.so.4
#16 0x00007f56cd3d77ad in QApplicationPrivate::notify_helper () from /usr/lib64/qt4/libQtGui.so.4
#17 0x00007f56cd3e007a in QApplication::notify () from /usr/lib64/qt4/libQtGui.so.4
#18 0x00007f56d25b5eaa in KApplication::notify (this=0x7fffdac0dd90, receiver=0x1945788, event=0x7fffdac0d6b0)
    at /var/tmp/portage/kde-base/kdelibs-4.2.96/work/kdelibs-4.2.96/kdeui/kernel/kapplication.cpp:302
#19 0x00007f56ccd0d673 in QCoreApplication::notifyInternal () from /usr/lib64/qt4/libQtCore.so.4
#20 0x00007f56ccd343ee in ?? () from /usr/lib64/qt4/libQtCore.so.4
#21 0x00007f56ccd346f8 in QEventDispatcherUNIX::processEvents () from /usr/lib64/qt4/libQtCore.so.4
#22 0x00007f56cd45cea2 in ?? () from /usr/lib64/qt4/libQtGui.so.4
#23 0x00007f56ccd0c072 in QEventLoop::processEvents () from /usr/lib64/qt4/libQtCore.so.4
#24 0x00007f56ccd0c205 in QEventLoop::exec () from /usr/lib64/qt4/libQtCore.so.4
#25 0x00007f56ccd0e184 in QCoreApplication::exec () from /usr/lib64/qt4/libQtCore.so.4
#26 0x0000000000404011 in main (argc=3, argv=0x7fffdac0df18) at /var/tmp/portage/kde-base/kmail-4.2.96/work/kmail-4.2.96/kmail/main.cpp:146

Reported using DrKonqi