Version:           4.0 beta3 (using 4.00.80 (KDE 4.0.80 >= 20080104), Gentoo)
Compiler:          i686-pc-linux-gnu-gcc
OS:                Linux (i686) release 2.6.23-gentoo-r3

Steps to reproduce:

1) Open Kontact
2) Open KMail
3) Click on any of the emails in your email account.
4) Create a new task from that email
5) Go to "Attachments" tab
6) Click on (open) the email message that is displayed there
7) See Kontact crash.

I use kdepimlibs r767495 and kdepim r765208.

Backtrace:
Application: Kontact (kontact), signal SIGABRT
Using host libthread_db library "/lib/libthread_db.so.1".
[Thread debugging using libthread_db enabled]
[New Thread 0xb531c6d0 (LWP 5980)]
[KCrash handler]
#6  0xffffe410 in __kernel_vsyscall ()
#7  0xb56b11f1 in *__GI_raise (sig=6)
    at ../nptl/sysdeps/unix/sysv/linux/raise.c:64
#8  0xb56b29b8 in *__GI_abort () at abort.c:88
#9  0xb7d82265 in qt_message_output (msgType=QtFatalMsg, 
    buf=0xbfa62a4c "ASSERT: \"!isEmpty()\" in file /usr/include/qt4/QtCore/qlist.h, line 242") at global/qglobal.cpp:2160
#10 0xb7d8232a in qFatal (msg=0xb7e8987c "ASSERT: \"%s\" in file %s, line %d")
    at global/qglobal.cpp:2392
#11 0xb7d82555 in qt_assert (assertion=0xb3bf5bed "!isEmpty()", 
    file=0xb3bf5954 "/usr/include/qt4/QtCore/qlist.h", line=242)
    at global/qglobal.cpp:1917
#12 0xb3afd95a in QList<QString>::first (this=0xbfa64b34)
    at /usr/include/qt4/QtCore/qlist.h:242
#13 0xb3b70cc0 in KOEditorAttachments::showAttachment (this=0x879cae0, 
    item=0x87aa040)
    at /var/tmp/portage/kde-base/kdepim-9999.4/work/kdepim-9999.4/korganizer/koeditorattachments.cpp:647
#14 0xb3b75732 in KOEditorAttachments::qt_metacall (this=0x879cae0, 
    _c=QMetaObject::InvokeMetaMethod, _id=2, _a=0xbfa6506c)
    at /var/tmp/portage/kde-base/kdepim-9999.4/work/kdepim_build/korganizer/koeditorattachments.moc:142
#15 0xb7e681f4 in QMetaObject::activate (sender=0x879d668, 
    from_signal_index=80, to_signal_index=80, argv=<value optimized out>)
    at kernel/qobject.cpp:3081
#16 0xb7e68d94 in QMetaObject::activate (sender=0x879d668, m=0xb6310bc0, 
    local_signal_index=0, argv=0xbfa6506c) at kernel/qobject.cpp:3140
#17 0xb62b33d1 in K3IconView::executed (this=0x879d668, _t1=0x87aa040)
    at /var/tmp/portage/kde-base/kdelibs-9999.4/work/kdelibs_build/kde3support/k3iconview.moc:141
#18 0xb62b554d in K3IconView::emitExecute (this=0x879d668, item=0x87aa040, 
    pos=@0xbfa656c0)
    at /var/tmp/portage/kde-base/kdelibs-9999.4/work/kdelibs-9999.4/kde3support/kdeui/k3iconview.cpp:252
#19 0xb62b55cf in K3IconView::slotMouseButtonClicked (this=0x879d668, btn=1, 
    item=0x87aa040, pos=@0xbfa656c0)
    at /var/tmp/portage/kde-base/kdelibs-9999.4/work/kdelibs-9999.4/kde3support/kdeui/k3iconview.cpp:328
#20 0xb62b60a2 in K3IconView::qt_metacall (this=0x879d668, 
    _c=QMetaObject::InvokeMetaMethod, _id=8, _a=0xbfa655d4)
    at /var/tmp/portage/kde-base/kdelibs-9999.4/work/kdelibs_build/kde3support/k3iconview.moc:102
#21 0xb7e681f4 in QMetaObject::activate (sender=0x879d668, 
    from_signal_index=62, to_signal_index=62, argv=<value optimized out>)
    at kernel/qobject.cpp:3081
#22 0xb7e68d94 in QMetaObject::activate (sender=0x879d668, m=0xb6683048, 
    local_signal_index=12, argv=0xbfa655d4) at kernel/qobject.cpp:3140
#23 0xb65f9030 in Q3IconView::mouseButtonClicked (this=0x879d668, _t1=1, 
    _t2=0x87aa040, _t3=@0xbfa656c0)
    at .moc/debug-shared/moc_q3iconview.cpp:388
#24 0xb645594b in Q3IconView::contentsMouseReleaseEvent (this=0x879d668, 
    e=0xbfa656a8) at itemviews/q3iconview.cpp:4459
#25 0xb62b517b in K3IconView::contentsMouseReleaseEvent (this=0x879d668, 
    e=0xbfa656a8)
    at /var/tmp/portage/kde-base/kdelibs-9999.4/work/kdelibs-9999.4/kde3support/kdeui/k3iconview.cpp:334
#26 0xb64e3fde in Q3ScrollView::viewportMouseReleaseEvent (this=0x879d668, 
    e=0xbfa65d84) at widgets/q3scrollview.cpp:1780
#27 0xb64e5206 in Q3ScrollView::eventFilter (this=0x879d668, obj=0x879dd40, 
    e=0xbfa65d84) at widgets/q3scrollview.cpp:1498
#28 0xb645f4a5 in Q3IconView::eventFilter (this=0x879d668, o=0x879dd40, 
    e=0xbfa65d84) at itemviews/q3iconview.cpp:5496
#29 0xb6d26d9b in QApplicationPrivate::notify_helper (this=0x8064960, 
    receiver=0x879dd40, e=0xbfa65d84) at kernel/qapplication.cpp:3548
#30 0xb6d28a2c in QApplication::notify (this=0xbfa66310, receiver=0x879dd40, 
    e=0xbfa65d84) at kernel/qapplication.cpp:3255
#31 0xb79d9543 in KApplication::notify (this=0xbfa66310, receiver=0x879dd40, 
    event=0xbfa65d84)
    at /var/tmp/portage/kde-base/kdelibs-9999.4/work/kdelibs-9999.4/kdeui/kernel/kapplication.cpp:310
#32 0xb7e54d7b in QCoreApplication::notifyInternal (this=0xbfa66310, 
    receiver=0x879dd40, event=0xbfa65d84) at kernel/qcoreapplication.cpp:530
#33 0xb6d8c628 in QETWidget::translateMouseEvent (this=0x879dd40, 
    event=0xbfa66148)
    at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:203
#34 0xb6d8ae8e in QApplication::x11ProcessEvent (this=0xbfa66310, 
    event=0xbfa66148) at kernel/qapplication_x11.cpp:2913
#35 0xb6db0c45 in QEventDispatcherX11::processEvents (this=0x805b2f0, 
    flags=@0xbfa66234) at kernel/qeventdispatcher_x11.cpp:125
#36 0xb7e54191 in QEventLoop::processEvents (this=0xbfa662a0, 
    flags=@0xbfa66268) at kernel/qeventloop.cpp:140
#37 0xb7e5429a in QEventLoop::exec (this=0xbfa662a0, flags=@0xbfa662a8)
    at kernel/qeventloop.cpp:186
#38 0xb7e56626 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:759
#39 0xb6d26487 in QApplication::exec () at kernel/qapplication.cpp:3053
#40 0x0804b3f5 in main (argc=1, argv=0xbfa664a4)
    at /var/tmp/portage/kde-base/kdepim-9999.4/work/kdepim-9999.4/kontact/src/main.cpp:162
#41 0xb569dfdc in __libc_start_main (main=0x804ab60 <main>, argc=1, 
    ubp_av=0xbfa664a4, init=0x804c180 <__libc_csu_init>, 
    fini=0x804c170 <__libc_csu_fini>, rtld_fini=0xb7f18100 <_dl_fini>, 
    stack_end=0xbfa6649c) at libc-start.c:229
#42 0x0804a791 in _start ()
#0  0xffffe410 in __kernel_vsyscall ()