Version:           2.1.1 (using 4.1.1 (KDE 4.1.1), Gentoo)
Compiler:          i686-pc-linux-gnu-gcc
OS:                Linux (i686) release 2.6.25-gentoo-r7

As discussed, in bug #168791 this is the bug for the backtrace I posted there. As this already was quite a while ago, I dont exactly know what I did, but it had to be something with adding a torrent to be downloaded via kget and selecting "redownload torrent" in kget. The backtrace for this crash was:

Application: KGet (kget), signal SIGABRT
[Thread debugging using libthread_db enabled]
[New Thread 0xb61cd700 (LWP 15380)]
[KCrash handler]
#6  0xffffe424 in __kernel_vsyscall ()
#7  0xb64fc690 in *__GI_raise (sig=6)
    at ../nptl/sysdeps/unix/sysv/linux/raise.c:64
#8  0xb64fded8 in *__GI_abort () at abort.c:88
#9  0xb750d097 in qt_message_output (msgType=QtFatalMsg, 
    buf=0xbffd6cac "ASSERT: \"extenderIndices.value(extender).isValid()\" in
file
/var/tmp/portage/kde-base/kdelibs-4.1.0/work/kdelibs-4.1.0/kdeui/itemviews/kextendableitemdelegate.cpp,
line 128") at global/qglobal.cpp:2058
#10 0xb750d14f in qFatal (msg=0xb7660ab4 "ASSERT: \"%s\" in file %s, line %d")
    at global/qglobal.cpp:2260
#11 0xb750d5cb in qt_assert (
    assertion=0xb7f882a0 "extenderIndices.value(extender).isValid()", 
    file=0xb7f88238
"/var/tmp/portage/kde-base/kdelibs-4.1.0/work/kdelibs-4.1.0/kdeui/itemviews/kextendableitemdelegate.cpp",
line=128)
    at global/qglobal.cpp:1828
#12 0xb7e3d55d in
KExtendableItemDelegate::Private::_k_extenderDestructionHandler
(this=0x81de4f8, destroyed=0x81c0e28)
    at
/var/tmp/portage/kde-base/kdelibs-4.1.0/work/kdelibs-4.1.0/kdeui/itemviews/kextendableitemdelegate.cpp:128
#13 0xb7e3d70c in KExtendableItemDelegate::qt_metacall (this=0x81e0308, 
    _c=QMetaObject::InvokeMetaMethod, _id=2, _a=0xbffd8e6c)
    at
/var/tmp/portage/kde-base/kdelibs-4.1.0/work/kdelibs_build/kdeui/kextendableitemdelegate.moc:74
#14 0x0807169b in TransfersViewDelegate::qt_metacall (this=0x81e0308, 
    _c=QMetaObject::InvokeMetaMethod, _id=12, _a=0xbffd8e6c)
    at
/var/tmp/portage/kde-base/kget-4.1.0/work/kget_build/kget/transfersviewdelegate.moc:159
#15 0xb7620530 in QMetaObject::activate (sender=0x81c0e28, 
    from_signal_index=<value optimized out>, to_signal_index=1, 
    argv=<value optimized out>) at kernel/qobject.cpp:3001
#16 0xb7620a4a in QMetaObject::activate (sender=0x81c0e28, m=0x80a12b0, 
    from_local_signal_index=0, to_local_signal_index=1, argv=0xbffd8e6c)
    at kernel/qobject.cpp:3091
#17 0xb7620acb in QObject::destroyed (this=0x81c0e28, _t1=0x81c0e28)
    at .moc/debug-shared/moc_qobject.cpp:115
#18 0xb76230f8 in ~QObject (this=0x81c0e28) at kernel/qobject.cpp:796
#19 0xb68921be in ~QWidget (this=0x81c0e28) at kernel/qwidget.cpp:1346
#20 0xb6bf322d in ~QGroupBox (this=0x81c0e28) at widgets/qgroupbox.cpp:219
#21 0xb761a2b2 in qDeleteInEventHandler (o=0x6) at kernel/qobject.cpp:3586
#22 0xb761c2ca in QObject::event (this=0x81c0e28, e=0x834da08)
    at kernel/qobject.cpp:1115
#23 0xb689d434 in QWidget::event (this=0x81c0e28, event=0x834da08)
    at kernel/qwidget.cpp:7310
#24 0xb6bf4bc5 in QGroupBox::event (this=0x81c0e28, e=0x834da08)
    at widgets/qgroupbox.cpp:400
#25 0xb68448a4 in QApplicationPrivate::notify_helper (this=0x80b2730, 
    receiver=0x81c0e28, e=0x834da08) at kernel/qapplication.cpp:3772
#26 0xb68489b2 in QApplication::notify (this=0xbffd9870, receiver=0x81c0e28, 
    e=0x834da08) at kernel/qapplication.cpp:3739
#27 0xb7e5c6c3 in KApplication::notify (this=0xbffd9870, receiver=0x81c0e28, 
    event=0x834da08)
    at
/var/tmp/portage/kde-base/kdelibs-4.1.0/work/kdelibs-4.1.0/kdeui/kernel/kapplication.cpp:311
#28 0xb760ad59 in QCoreApplication::notifyInternal (this=0xbffd9870, 
    receiver=0x81c0e28, event=0x834da08) at kernel/qcoreapplication.cpp:587
#29 0xb760c006 in QCoreApplicationPrivate::sendPostedEvents (receiver=0x0, 
    event_type=0, data=0x80a2900) at kernel/qcoreapplication.h:215
#30 0xb7639eca in QEventDispatcherUNIX::processEvents (this=0x80b1698, 
    flags=@0xbffd9758) at kernel/qeventdispatcher_unix.cpp:867
#31 0xb68d4f61 in QEventDispatcherX11::processEvents (this=0x80b1698, 
    flags=@0xbffd9788) at kernel/qeventdispatcher_x11.cpp:154
#32 0xb760a0d3 in QEventLoop::processEvents (this=0xbffd9800, 
    flags=@0xbffd97c8) at kernel/qeventloop.cpp:149
#33 0xb760a246 in QEventLoop::exec (this=0xbffd9800, flags=@0xbffd9808)
    at kernel/qeventloop.cpp:200
#34 0xb760c401 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:845
#35 0xb684423f in QApplication::exec () at kernel/qapplication.cpp:3304
#36 0x080907be in main (argc=5, argv=0xbffd9a54)
    at /var/tmp/portage/kde-base/kget-4.1.0/work/kget-4.1.0/kget/main.cpp:153
#0  0xffffe424 in __kernel_vsyscall ()