Application that crashed: kpackagekit
Version of the application: 0.4.2
KDE Version: 4.3.2 (KDE 4.3.2)
Qt Version: 4.5.2
Operating System: Linux 2.6.31-16-generic i686
Distribution: Ubuntu 9.10

What I was doing when the application crashed:
After getting a notification about new updates being available, clicking it to open KPackageKit, clicking "Select all updates" and clicking "OK" (or was it "Apply"? can't remember), the front end segfaulted but the update continued to run in the background and, apparently, finished successfully some minutes later.

(The crash reporting assistant gave me a list of dozens of "KPackageKit crash" bugs to check against.  This is quite possibly a dupe of one of them, but I can't figure out which one.  Sorry.)

 -- Backtrace:
Application: KPackageKit (kpackagekit), signal: Segmentation fault
[KCrash Handler]
#6  QWidget::window (this=0x9c43b70) at kernel/qwidget.cpp:3883
#7  0x00c49d2e in QApplicationPrivate::dispatchEnterLeave (enter=0x9b9a560, leave=0x9c43b70) at kernel/qapplication.cpp:2527
#8  0x00c4a17a in QApplicationPrivate::sendMouseEvent (receiver=0x9b9a560, event=0xbff07630, alienWidget=0x9b9a560, nativeWidget=0x9b6e930, buttonDown=0x14bdaa0, lastMouseReceiver=...)
    at kernel/qapplication.cpp:2908
#9  0x00cb87c0 in QETWidget::translateMouseEvent (this=0x9b6e930, event=0xbff08c7c) at kernel/qapplication_x11.cpp:4409
#10 0x00cb7c4b in QApplication::x11ProcessEvent (this=0xbff09010, event=0xbff08c7c) at kernel/qapplication_x11.cpp:3428
#11 0x00ce4502 in x11EventSourceDispatch (s=0x9a7cb00, callback=0, user_data=0x0) at kernel/qguieventdispatcher_glib.cpp:146
#12 0x04d3be78 in child_watch_helper_thread (data=0x9a7be40) at /build/buildd/glib2.0-2.22.3/glib/gmain.c:3836
#13 0x04d3f720 in append_escaped_text (text=0x1 <Address 0x1 out of bounds>, length=161954984) at /build/buildd/glib2.0-2.22.3/glib/gmarkup.c:2042
#14 IA__g_markup_escape_text (text=0x1 <Address 0x1 out of bounds>, length=161954984) at /build/buildd/glib2.0-2.22.3/glib/gmarkup.c:2117
#15 0x04d3f853 in g_string_append_c_inline (format=0x9a7be40 "", args=0x1 <Address 0x1 out of bounds>) at /build/buildd/glib2.0-2.22.3/glib/gstring.h:149
#16 IA__g_markup_vprintf_escaped (format=0x9a7be40 "", args=0x1 <Address 0x1 out of bounds>) at /build/buildd/glib2.0-2.22.3/glib/gmarkup.c:2314
#17 0x0642802c in QEventDispatcherGlib::processEvents (this=0x9a56f08, flags=...) at kernel/qeventdispatcher_glib.cpp:327
#18 0x00ce3be5 in QGuiEventDispatcherGlib::processEvents (this=0x9a56f08, flags=...) at kernel/qguieventdispatcher_glib.cpp:202
#19 0x063fbc79 in QEventLoop::processEvents (this=0xbff08f74, flags=) at kernel/qeventloop.cpp:149
#20 0x063fc0ca in QEventLoop::exec (this=0xbff08f74, flags=...) at kernel/qeventloop.cpp:201
#21 0x063fe53f in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#22 0x00c42dd7 in QApplication::exec () at kernel/qapplication.cpp:3525
#23 0x0804e47b in _start ()

Reported using DrKonqi