Version:           desconocido (using KDE 3.5.5, Debian Package 4:3.5.5a.dfsg.1-5 (4.0))
Compiler:          Target: i486-linux-gnu
OS:                Linux (i686) release 2.6.18p4s

I changed to the notes part in kontact and had this backtrace:

Using host libthread_db library "/lib/tls/i686/cmov/libthread_db.so.1".
[Thread debugging using libthread_db enabled]
[New Thread -1510992192 (LWP 8815)]
[New Thread -1575621712 (LWP 8938)]
[New Thread -1552806992 (LWP 8819)]
[New Thread -1544414288 (LWP 8818)]
[New Thread -1536021584 (LWP 8817)]
[New Thread -1527628880 (LWP 8816)]
[KCrash handler]
#6  0xa7737bd5 in malloc_usable_size () from /lib/tls/i686/cmov/libc.so.6
#7  0xa7739bb8 in free () from /lib/tls/i686/cmov/libc.so.6
#8  0xa773b87f in malloc () from /lib/tls/i686/cmov/libc.so.6
#9  0xa78e68b8 in operator new () from /usr/lib/libstdc++.so.6
#10 0xa78e69ed in operator new[] () from /usr/lib/libstdc++.so.6
#11 0xa72aa617 in QString::setLength (this=0xafcf7190, newLen=142049074)
    at tools/qstring.cpp:1703
#12 0xa72ad2ce in replaceArgEscapes (s=@0xafcf7194, d=@0xafcf7150, 
    field_width=0, arg=@0x8762b1c, larg=@0x8762b1c) at tools/qstring.cpp:1891
#13 0xa72ad645 in QString::arg (this=0xafcf7194, a=@0x8762b1c, fieldWidth=0)
    at tools/qstring.cpp:2001
#14 0xa75effce in KCatalogue (this=0xafcf71e4, name=@0x80b4c60, 
    language=@0x80b4eb0)
    at /home/ana/Debian/kdelibs/kdelibs-3.5.5a.dfsg.1/./kdecore/kcatalogue.cpp:67
#15 0xa7602273 in KLocale::updateCatalogues (this=0x80c61f0)
    at /home/ana/Debian/kdelibs/kdelibs-3.5.5a.dfsg.1/./kdecore/klocale.cpp:668
#16 0xa760669a in KLocale::insertCatalogue (this=0x80c61f0, 
    catalog=@0xafcf72a8)
    at /home/ana/Debian/kdelibs/kdelibs-3.5.5a.dfsg.1/./kdecore/klocale.cpp:634
#17 0xa7d4fe69 in KParts::PartBase::setInstance (this=0x8ea6da0, 
    inst=0x8f1e840, bLoadPlugins=true)
    at /home/ana/Debian/kdelibs/kdelibs-3.5.5a.dfsg.1/./kparts/part.cpp:113
#18 0xa7d39341 in KParts::PartBase::setInstance (this=0x8ea6da0, 
    inst=0x8f1e840)
    at /home/ana/Debian/kdelibs/kdelibs-3.5.5a.dfsg.1/./kparts/part.cpp:107
#19 0xa5765bcc in KNotesPart (this=0x8ea6d78, parent=0x81ec0a0, 
    name=0xa5774e8e "notes")
    at /tmp/buildd/kdepim-3.5.5.dfsg.1/./kontact/plugins/knotes/knotes_part.cpp:49
#20 0xa576613e in KNotesPlugin::createPart (this=0x81ec0a0)
    at /tmp/buildd/kdepim-3.5.5.dfsg.1/./kontact/plugins/knotes/knotes_plugin.cpp:56
#21 0xa7d73172 in Kontact::Plugin::part (this=0x81ec0a0)
    at /tmp/buildd/kdepim-3.5.5.dfsg.1/./kontact/interfaces/plugin.cpp:144
#22 0x080610af in Kontact::MainWindow::selectPlugin (this=0x80cd1b0, 
    plugin=0x81ec0a0)
    at /tmp/buildd/kdepim-3.5.5.dfsg.1/./kontact/src/mainwindow.cpp:536
#23 0x08062f42 in Kontact::MainWindow::qt_invoke (this=0x80cd1b0, _id=78, 
    _o=0xafcf75f4) at ./mainwindow.moc:137
#24 0xa6f92d4f in QObject::activate_signal (this=0x8100490, clist=0x8106308, 
    o=0xafcf75f4) at kernel/qobject.cpp:2356
#25 0x08058fa2 in Kontact::SidePaneBase::pluginSelected (this=0x8100490, 
    t0=0x81ec0a0) at ./sidepanebase.moc:114
#26 0x08059001 in Kontact::SidePaneBase::qt_emit (this=0x8100490, _id=2, 
    _o=0xafcf76d4) at ./sidepanebase.moc:133
#27 0x0805904f in Kontact::IconSidePane::qt_emit (this=0x8100490, _id=2, 
    _o=0xafcf76d4) at ./iconsidepane.moc:244
#28 0xa6f92d23 in QObject::activate_signal (this=0x8100930, clist=0x8104a48, 
    o=0xafcf76d4) at kernel/qobject.cpp:2354
#29 0x08059602 in Kontact::Navigator::pluginActivated (this=0x8100930, 
    t0=0x81ec0a0) at ./iconsidepane.moc:122
#30 0x0805b71f in Kontact::Navigator::qt_invoke (this=0x8100930, _id=78, 
    _o=0xafcf7798) at ./iconsidepane.moc:128
#31 0xa6f92d4f in QObject::activate_signal (this=0x8100930, clist=0x8104488, 
    o=0xafcf7798) at kernel/qobject.cpp:2356
#32 0xa73312c6 in QListBox::selectionChanged (this=0x8100930, t0=0x82ca268)
    at .moc/debug-shared-mt/moc_qlistbox.cpp:318
#33 0xa7083342 in QListBox::setCurrentItem (this=0x8100930, i=0x82ca268)
    at widgets/qlistbox.cpp:1864
#34 0xa707614b in QListBox::setCurrentItem (this=0x8100930, index=7)
    at widgets/qlistbox.cpp:1833
#35 0x0805b744 in Kontact::Navigator::qt_invoke (this=0x8100930, _id=82, 
    _o=0xafcf7928) at ./iconsidepane.moc:132
#36 0xa6f92d4f in QObject::activate_signal (this=0x8104628, clist=0x8104418, 
    o=0xafcf7928) at kernel/qobject.cpp:2356
#37 0xa6f93656 in QObject::activate_signal (this=0x8104628, signal=2, param=7)
    at kernel/qobject.cpp:2449
#38 0xa731c2e1 in QSignalMapper::mapped (this=0x8104628, t0=7)
    at .moc/debug-shared-mt/moc_qsignalmapper.cpp:96
#39 0xa6fb2f41 in QSignalMapper::map (this=0x8104628)
    at kernel/qsignalmapper.cpp:146
#40 0xa731c20e in QSignalMapper::qt_invoke (this=0x8104628, _id=2, 
    _o=0xafcf7a5c) at .moc/debug-shared-mt/moc_qsignalmapper.cpp:108
#41 0xa6f92d4f in QObject::activate_signal (this=0x82c98f8, clist=0x82c9a10, 
    o=0xafcf7a5c) at kernel/qobject.cpp:2356
#42 0xa6f937e0 in QObject::activate_signal (this=0x82c98f8, signal=2)
    at kernel/qobject.cpp:2325
#43 0xa67aa259 in KAction::activated (this=0x82c98f8) at ./kaction.moc:176
#44 0xa67df971 in KAction::slotActivated (this=0x82c98f8)
    at /home/ana/Debian/kdelibs/kdelibs-3.5.5a.dfsg.1/./kdeui/kaction.cpp:1102
#45 0xa67df90d in KAction::slotButtonClicked (this=0x82c98f8, 
    state=LeftButton)
    at /home/ana/Debian/kdelibs/kdelibs-3.5.5a.dfsg.1/./kdeui/kaction.cpp:1147
#46 0xa68bffe6 in KAction::qt_invoke (this=0x82c98f8, _id=17, _o=0xafcf7b60)
    at ./kaction.moc:220
#47 0xa6f92d4f in QObject::activate_signal (this=0x82d1518, clist=0x82d1e48, 
    o=0xafcf7b60) at kernel/qobject.cpp:2356
#48 0xa67e104e in KToolBarButton::buttonClicked (this=0x82d1518, t0=-11, 
    t1=LeftButton) at ./ktoolbarbutton.moc:154
#49 0xa67e1358 in KToolBarButton::mouseReleaseEvent (this=0x82d1518, 
    e=0xafcf8024)
    at /home/ana/Debian/kdelibs/kdelibs-3.5.5a.dfsg.1/./kdeui/ktoolbarbutton.cpp:479
#50 0xa6fc96f0 in QWidget::event (this=0x82d1518, e=0xafcf8024)
    at kernel/qwidget.cpp:4702
#51 0xa685bae1 in KToolBarButton::event (this=0x1, e=0x8000000)
    at /home/ana/Debian/kdelibs/kdelibs-3.5.5a.dfsg.1/./kdeui/ktoolbarbutton.cpp:651
#52 0xa6f2ac26 in QApplication::internalNotify (this=0xafcf85fc, 
    receiver=0x82d1518, e=0xafcf8024) at kernel/qapplication.cpp:2635
#53 0xa6f2cdc9 in QApplication::notify (this=0xafcf85fc, receiver=0x82d1518, 
    e=0xafcf8024) at kernel/qapplication.cpp:2421
#54 0xa7652e0e in KApplication::notify (this=0xafcf85fc, receiver=0x82d1518, 
    event=0xafcf8024)
    at /home/ana/Debian/kdelibs/kdelibs-3.5.5a.dfsg.1/./kdecore/kapplication.cpp:550
#55 0xa6ebe495 in QApplication::sendSpontaneousEvent (receiver=0x82d1518, 
    event=0xafcf8024) at kernel/qapplication.h:523
#56 0xa6ebd12f in QETWidget::translateMouseEvent (this=0x82d1518, 
    event=0xafcf8458) at kernel/qapplication_x11.cpp:4301
#57 0xa6ebb6b0 in QApplication::x11ProcessEvent (this=0xafcf85fc, 
    event=0xafcf8458) at kernel/qapplication_x11.cpp:3478
#58 0xa6ed1d02 in QEventLoop::processEvents (this=0x808e670, flags=4)
    at kernel/qeventloop_x11.cpp:192
#59 0xa6f45179 in QEventLoop::enterLoop (this=0x808e670)
    at kernel/qeventloop.cpp:198
#60 0xa6f44f9a in QEventLoop::exec (this=0x808e670)
    at kernel/qeventloop.cpp:145
#61 0xa6f2c7bf in QApplication::exec (this=0xafcf85fc)
    at kernel/qapplication.cpp:2758
#62 0x0805ac3f in main (argc=)
    at /tmp/buildd/kdepim-3.5.5.dfsg.1/./kontact/src/main.cpp:161
#63 0xa76e8ea8 in __libc_start_main () from /lib/tls/i686/cmov/libc.so.6
#64 0x080582b1 in _start () at ../sysdeps/i386/elf/start.S:119