Version:           1.2.3 (using KDE KDE 3.5.5)
Installed from:    Debian stable Packages
OS:                Linux

I opened kontact. Then I checked my RSS feeds with akregator, opening the interesting ones to be read in a moment in konqueror.  I then switched to the kmail part of kontact, forwarded some spam from two different DIMAP folders to a local spam reporting/learning service and then deleted the spam, and closed the kontact window (kmail and akregator icons remained in my tray).  A fix minutes later when I was done with the articles and fiddling with ktorrent, kontact crashes with this backtrace:

Using host libthread_db library "/lib/libthread_db.so.1".
[Thread debugging using libthread_db enabled]
[New Thread 47427029670608 (LWP 10742)]
[New Thread 1107310944 (LWP 10746)]
[New Thread 1098918240 (LWP 10745)]
[New Thread 1090525536 (LWP 10744)]
[New Thread 1082132832 (LWP 10743)]
[KCrash handler]
#5  FolderStorage::moveMsg (this=0xadd6b0, aMsg=0x0, 
    aIndex_ret=0x7fff39950378)
    at /build/buildd/kdepim-3.5.5.dfsg.1/./kmail/kmmsgbase.h:146
#6  0x00002b2279b7a2b2 in KMMoveCommand::execute (this=0x19e9770)
    at /build/buildd/kdepim-3.5.5.dfsg.1/./kmail/kmcommands.cpp:1962
#7  0x00002b2279b06d10 in KMCommand::slotPostTransfer (this=0x19e9770, 
    result=KMCommand::OK)
    at /build/buildd/kdepim-3.5.5.dfsg.1/./kmail/kmcommands.cpp:256
#8  0x00002b2279b7bac3 in KMCommand::qt_invoke (this=0x19e9770, _id=5, 
    _o=0x7fff399504d0) at ./kmcommands.moc:148
#9  0x00002b2279b7bd49 in KMMenuCommand::qt_invoke (this=0xadd6b0, _id=0, 
    _o=0x7fff39950378) at ./kmcommands.moc:2509
#10 0x00002b2279b7bdcd in KMMoveCommand::qt_invoke (this=0x19e9770, _id=5, 
    _o=0x7fff399504d0) at ./kmcommands.moc:2692
#11 0x00002b2272f0ec26 in QObject::activate_signal (this=0x19e9770, 
    clist=0x7537d0, o=0x7fff399504d0) at kernel/qobject.cpp:2356
#12 0x00002b2279b06e3c in KMCommand::messagesTransfered (
    this=<value optimized out>, t0=KMCommand::OK) at ./kmcommands.moc:126
#13 0x00002b2279bcdf7d in KMCommand::transferSelectedMsgs (this=0x19e9770)
    at /build/buildd/kdepim-3.5.5.dfsg.1/./kmail/kmcommands.cpp:351
#14 0x00002b2279b7bad7 in KMCommand::qt_invoke (this=0x19e9770, _id=4, 
    _o=0x7fff399506b0) at ./kmcommands.moc:147
#15 0x00002b2279b7bd49 in KMMenuCommand::qt_invoke (this=0xadd6b0, _id=0, 
    _o=0x7fff39950378) at ./kmcommands.moc:2509
#16 0x00002b2279b7bdcd in KMMoveCommand::qt_invoke (this=0x19e9770, _id=4, 
    _o=0x7fff399506b0) at ./kmcommands.moc:2692
#17 0x00002b2272f0ec26 in QObject::activate_signal (this=0x6b8150, 
    clist=0xe65570, o=0x7fff399506b0) at kernel/qobject.cpp:2356
#18 0x00002b227327c108 in QSignal::signal (this=0x6b8150, t0=@0x6b81a0)
    at .moc/debug-shared-mt/moc_qsignal.cpp:100
#19 0x00002b2272f2dcf7 in QSignal::activate (this=0x6b8150)
    at kernel/qsignal.cpp:212
#20 0x00002b2272f34cb6 in QSingleShotTimer::event (this=0x6b8100)
    at kernel/qtimer.cpp:286
#21 0x00002b2272eaa262 in QApplication::internalNotify (this=0x7fff39950f80, 
    receiver=0x6b8100, e=0x7fff39950ba0) at kernel/qapplication.cpp:2635
#22 0x00002b2272eac00c in QApplication::notify (this=0x7fff39950f80, 
    receiver=0x6b8100, e=0x7fff39950ba0) at kernel/qapplication.cpp:2358
#23 0x00002b22728048be in KApplication::notify (this=0x7fff39950f80, 
    receiver=0x6b8100, event=0x7fff39950ba0)
    at /build/buildd/kdelibs-3.5.5a.dfsg.1/./kdecore/kapplication.cpp:550
#24 0x00002b2272e3d802 in QApplication::sendEvent (receiver=0x6b8100, 
    event=0x7fff39950ba0) at ../include/qapplication.h:520
#25 0x00002b2272e9d57c in QEventLoop::activateTimers (this=0x57a700)
    at kernel/qeventloop_unix.cpp:556
#26 0x00002b2272e51584 in QEventLoop::processEvents (this=0x57a700, flags=4)
    at kernel/qeventloop_x11.cpp:389
#27 0x00002b2272ec37ee in QEventLoop::enterLoop (this=0x57a700)
    at kernel/qeventloop.cpp:198
#28 0x00002b2272ec35f7 in QEventLoop::exec (this=0x57a700)
    at kernel/qeventloop.cpp:145
#29 0x00002b2272eabd40 in QApplication::exec (this=0x7fff39950f80)
    at kernel/qapplication.cpp:2758
#30 0x000000000041730b in main (argc=<value optimized out>, 
    argv=0x7fff39951378)
    at /build/buildd/kdepim-3.5.5.dfsg.1/./kontact/src/main.cpp:161
#31 0x00002b22724024ca in __libc_start_main () from /lib/libc.so.6
#32 0x0000000000414b3a in _start () at ../sysdeps/x86_64/elf/start.S:113

I reopened kontact, but did nothing 'cept close the window (still having my tray icons) and it crashed again, but I neglicted to get a backtrace on that.