Application that crashed: @^
Version of the application: 4.0.0
KDE Version: 4.3.5 (KDE 4.3.5)
Qt Version: 4.5.3
Operating System: Linux 2.6.31.13-desktop-1mnb x86_64
Distribution: "Mandriva Linux 2010.0"

What I was doing when the application crashed:
1. Open KVirc
2. Connect to some server.
3. Click "New context" button.
4. Connect to another server in window created by "New context"
5. In "Window List" click right mouse button on the main "window" (represented by the icon of server) of a new connection and select "Close window"

The names of the menus will vary because I use the Polish version of kvirc. Sorry if what I wrote is not entirely clear but my English is not too good:)

 -- Backtrace:
Application: KVIrc (@^), signal: Segmentation fault
[KCrash Handler]
#5  QWidget::close (this=0x0) at kernel/qwidget.cpp:7198
#6  0x00000000004fa321 in KviMdiChild::closeEvent (this=<value optimized out>, e=0x7fff3100a0c0) at /usr/src/debug/kvirc/src/kvirc/ui/kvi_mdichild.cpp:112
#7  0x00007f0e1edd84f8 in QWidget::event (this=0x19b27d0, event=0x7fff3100a0c0) at kernel/qwidget.cpp:7704
#8  0x00007f0e1f16bd1b in QMdiSubWindow::event (this=0x19b27d0, event=0x7fff3100a0c0) at widgets/qmdisubwindow.cpp:2919
#9  0x00007f0e1ed8a12c in QApplicationPrivate::notify_helper (this=0x936ce0, receiver=0x19b27d0, e=0x7fff3100a0c0) at kernel/qapplication.cpp:4065
#10 0x00007f0e1ed913fe in QApplication::notify (this=0x9367e0, receiver=0x19b27d0, e=0x7fff3100a0c0) at kernel/qapplication.cpp:4030
#11 0x00007f0e1d9883f6 in KApplication::notify (this=0x9367e0, receiver=0x19b27d0, event=0x7fff3100a0c0) at /usr/src/debug/kdelibs-4.3.5/kdeui/kernel/kapplication.cpp:302
#12 0x00007f0e1e34c6ac in QCoreApplication::notifyInternal (this=0x9367e0, receiver=0x19b27d0, event=0x7fff3100a0c0) at kernel/qcoreapplication.cpp:610
#13 0x00007f0e1eddd901 in QWidgetPrivate::close_helper (this=0x19b2a80, mode=QWidgetPrivate::CloseWithSpontaneousEvent) at ../../src/corelib/kernel/qcoreapplication.h:216
#14 0x00007f0e1ede4d96 in QApplication::x11ClientMessage (this=<value optimized out>, w=0x19b27d0, event=0x13, passive_only=8) at kernel/qapplication_x11.cpp:5293
#15 0x00007f0e1edf5714 in QApplication::x11ProcessEvent (this=<value optimized out>, event=0x7fff3100b9a0) at kernel/qapplication_x11.cpp:3684
#16 0x00007f0e1ee1de9c in x11EventSourceDispatch (s=<value optimized out>, callback=<value optimized out>, user_data=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:146
#17 0x00007f0e1aa414ce in IA__g_main_context_dispatch (context=0x939930) at gmain.c:1960
#18 0x00007f0e1aa44e98 in g_main_context_iterate (context=0x939930, block=<value optimized out>, dispatch=<value optimized out>, self=<value optimized out>) at gmain.c:2591
#19 0x00007f0e1aa44fc0 in IA__g_main_context_iteration (context=0x939930, may_block=1) at gmain.c:2654
#20 0x00007f0e1e374c73 in QEventDispatcherGlib::processEvents (this=0x9075e0, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:406
#21 0x00007f0e1ee1d64e in QGuiEventDispatcherGlib::processEvents (this=0x0, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:202
#22 0x00007f0e1e34afe2 in QEventLoop::processEvents (this=<value optimized out>, flags=) at kernel/qeventloop.cpp:149
#23 0x00007f0e1e34b3b4 in QEventLoop::exec (this=0x7fff3100bcd0, flags=) at kernel/qeventloop.cpp:201
#24 0x00007f0e1e34d569 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#25 0x000000000062873d in main (argc=2, argv=<value optimized out>) at /usr/src/debug/kvirc/src/kvirc/kernel/kvi_main.cpp:417

Reported using DrKonqi