Version:           1.9.50 (using 4.00.80 (KDE 4.0.80 >= 20080104), Gentoo)
Compiler:          i686-pc-linux-gnu-gcc
OS:                Linux (i686) release 2.6.22-gentoo-r9

Today when I was moving mail around in Kontact in order to try to reproduce bug #156291 KMail all of a sudden (seemingly randomly) crashed with the following backtrace:

Using host libthread_db library "/lib/libthread_db.so.1".
[Thread debugging using libthread_db enabled]
[New Thread 0xb53fe6d0 (LWP 26320)]
[KCrash handler]
#6  KMail::ActionScheduler::processMessage (this=0x84e3630)
    at /var/tmp/portage/kde-base/kdepim-9999.4/work/kdepim-9999.4/kmail/actionscheduler.cpp:533
#7  0xb3569181 in KMail::ActionScheduler::qt_metacall (this=0x84e3630, 
    _c=QMetaObject::InvokeMetaMethod, _id=18, _a=0xbf9e8434)
    at /var/tmp/portage/kde-base/kdepim-9999.4/work/kdepim_build/kmail/actionscheduler.moc:118
#8  0xb7f441f4 in QMetaObject::activate (sender=0x84deeb8, 
    from_signal_index=4, to_signal_index=4, argv=<value optimized out>)
    at kernel/qobject.cpp:3081
#9  0xb7f44d94 in QMetaObject::activate (sender=0x84deeb8, m=0xb7fe39e4, 
    local_signal_index=0, argv=0x0) at kernel/qobject.cpp:3140
#10 0xb7f65083 in QTimer::timeout (this=0x84deeb8)
    at .moc/debug-shared/moc_qtimer.cpp:125
#11 0xb7f4da2e in QTimer::timerEvent (this=0x84deeb8, e=0xbf9e8968)
    at kernel/qtimer.cpp:259
#12 0xb7f42269 in QObject::event (this=0x84deeb8, e=0x8065138)
    at kernel/qobject.cpp:1086
#13 0xb6e04e8a in QApplicationPrivate::notify_helper (this=0x8060068, 
    receiver=0x84deeb8, e=0xbf9e8968) at kernel/qapplication.cpp:3556
#14 0xb6e0677a in QApplication::notify (this=0xbf9e8bf0, receiver=0x84deeb8, 
    e=0xbf9e8968) at kernel/qapplication.cpp:3115
#15 0xb7ab6fb3 in KApplication::notify (this=0xbf9e8bf0, receiver=0x84deeb8, 
    event=0xbf9e8968)
    at /var/tmp/portage/kde-base/kdelibs-9999.4/work/kdelibs-9999.4/kdeui/kernel/kapplication.cpp:314
#16 0xb7f30d7b in QCoreApplication::notifyInternal (this=0xbf9e8bf0, 
    receiver=0x84deeb8, event=0xbf9e8968) at kernel/qcoreapplication.cpp:530
#17 0xb7f59efb in QTimerInfoList::activateTimers (this=0x80607e4)
    at kernel/qcoreapplication.h:200
#18 0xb7f59fd1 in QEventDispatcherUNIX::activateTimers (this=0x805f170)
    at kernel/qeventdispatcher_unix.cpp:828
#19 0xb7f5a9ab in QEventDispatcherUNIX::processEvents (this=0x805f170, 
    flags=@0xbf9e8ae8) at kernel/qeventdispatcher_unix.cpp:890
#20 0xb6e8ecce in QEventDispatcherX11::processEvents (this=0x805f170, 
    flags=@0xbf9e8b14) at kernel/qeventdispatcher_x11.cpp:145
#21 0xb7f30191 in QEventLoop::processEvents (this=0xbf9e8b80, 
    flags=@0xbf9e8b48) at kernel/qeventloop.cpp:140
#22 0xb7f3029a in QEventLoop::exec (this=0xbf9e8b80, flags=@0xbf9e8b88)
    at kernel/qeventloop.cpp:186
#23 0xb7f32626 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:759
#24 0xb6e04487 in QApplication::exec () at kernel/qapplication.cpp:3053
#25 0x0804b3f5 in main (argc=1, argv=0xbf9e8d84)
    at /var/tmp/portage/kde-base/kdepim-9999.4/work/kdepim-9999.4/kontact/src/main.cpp:162
#26 0xb577ffdc in __libc_start_main (main=0x804ab60 <main>, argc=1, 
    ubp_av=0xbf9e8d84, init=0x804c180 <__libc_csu_init>, 
    fini=0x804c170 <__libc_csu_fini>, rtld_fini=0xb7ff4100 <_dl_fini>, 
    stack_end=0xbf9e8d7c) at libc-start.c:229
#27 0x0804a791 in _start ()
#0  0xffffe410 in __kernel_vsyscall ()