Application: ktorrent (4.0.0)
KDE Platform Version: 4.4.4 (KDE 4.4.4)
Qt Version: 4.6.3
Operating System: Linux 2.6.32-5-amd64 x86_64
Distribution: Debian GNU/Linux testing (squeeze)

-- Information about the crash:
This problem is reproducible.  Ktorrent works fine on its own, but as soon as I enable the WebUI plugin from the Plugins tab, Ktorrent crashes.  A backtrace yielded the results attached to this report.

I am running KTorrent 4.0.0-1, on KDE 4.4.4.  
Kernel: 2.6.32-5-amd64
Libqt4-core version  4:4.6.3-1

Please contact me if you need me to dig for more info, d3athp3nguin@gmail.com

The crash can be reproduced every time.

 -- Backtrace:
Application: KTorrent (ktorrent), signal: Segmentation fault
The current source language is "auto; currently asm".
[KCrash Handler]
#5  QSocketNotifier::setEnabled (this=0x0, enable=false) at kernel/qsocketnotifier.cpp:286
#6  0x00007f7c1a2b50f0 in ~HttpServer (this=0x2796480, __in_chrg=<value optimized out>) at ../../../plugins/webinterface/httpserver.cpp:114
#7  0x00007f7c1a2bc403 in kt::WebInterfacePlugin::initServer (this=0x2785a00) at ../../../plugins/webinterface/webinterfaceplugin.cpp:89
#8  0x00007f7c1a2bc6d7 in kt::WebInterfacePlugin::load (this=0x2785a00) at ../../../plugins/webinterface/webinterfaceplugin.cpp:56
#9  0x00007f7c36300a72 in kt::PluginManager::load (this=0x1abc6a0, pi=<value optimized out>, idx=7) at ../../libktcore/plugin/pluginmanager.cpp:124
#10 0x00007f7c36300e9d in kt::PluginManager::loadPlugins (this=0x1abc6a0) at ../../libktcore/plugin/pluginmanager.cpp:88
#11 0x00007f7c362d6770 in kt::PluginActivity::qt_metacall (this=0x1e49890, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=<value optimized out>) at moc_pluginactivity.cpp:72
#12 0x00007f7c340f3346 in QMetaObject::activate (sender=0x1e49990, m=<value optimized out>, local_signal_index=<value optimized out>, argv=0x1) at kernel/qobject.cpp:3295
#13 0x00007f7c3186b32f in KPluginSelector::changed (this=0x0, _t1=true) at ./kpluginselector.moc:87
#14 0x00007f7c3186b400 in KPluginSelector::qt_metacall (this=0x1e49990, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0x7fff46d75250) at ./kpluginselector.moc:74
#15 0x00007f7c340f3346 in QMetaObject::activate (sender=0x1e55790, m=<value optimized out>, local_signal_index=<value optimized out>, argv=0x1) at kernel/qobject.cpp:3295
#16 0x00007f7c3186b39f in KPluginSelector::Private::PluginDelegate::changed (this=0x0, _t1=true) at ./kpluginselector_p.moc:212
#17 0x00007f7c31872cec in KPluginSelector::Private::PluginDelegate::qt_metacall (this=0x1e55790, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0x7fff46d75390)
    at ./kpluginselector_p.moc:197
#18 0x00007f7c340f3346 in QMetaObject::activate (sender=0x2457a70, m=<value optimized out>, local_signal_index=<value optimized out>, argv=0x1) at kernel/qobject.cpp:3295
#19 0x00007f7c33b1d572 in QAbstractButton::clicked (this=0x0, _t1=true) at .moc/release-shared/moc_qabstractbutton.cpp:206
#20 0x00007f7c33835a5b in QAbstractButtonPrivate::emitClicked (this=0x246c440) at widgets/qabstractbutton.cpp:546
#21 0x00007f7c338368fb in QAbstractButtonPrivate::click (this=0x246c440) at widgets/qabstractbutton.cpp:539
#22 0x00007f7c33836b6c in QAbstractButton::mouseReleaseEvent (this=0x2457a70, e=0x7fff46d75e60) at widgets/qabstractbutton.cpp:1121
#23 0x00007f7c334d6602 in QWidget::event (this=0x2457a70, event=0x7fff46d75e60) at kernel/qwidget.cpp:8044
#24 0x00007f7c3348032c in QApplicationPrivate::notify_helper (this=0x1abfc10, receiver=0x2457a70, e=0x7fff46d75e60) at kernel/qapplication.cpp:4302
#25 0x00007f7c33486fdb in QApplication::notify (this=0x7fff46d76990, receiver=0x2457a70, e=0x7fff46d75e60) at kernel/qapplication.cpp:3867
#26 0x00007f7c3572e436 in KApplication::notify (this=0x7fff46d76990, receiver=0x2457a70, event=0x7fff46d75e60) at ../../kdeui/kernel/kapplication.cpp:302
#27 0x00007f7c340e015c in QCoreApplication::notifyInternal (this=0x7fff46d76990, receiver=0x2457a70, event=0x7fff46d75e60) at kernel/qcoreapplication.cpp:726
#28 0x00007f7c334861be in QCoreApplication::sendEvent (receiver=0x2457a70, event=0x7fff46d75e60, alienWidget=0x2457a70, nativeWidget=0x1c1bff0, buttonDown=<value optimized out>, 
    lastMouseReceiver=<value optimized out>, spontaneous=true) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:215
#29 QApplicationPrivate::sendMouseEvent (receiver=0x2457a70, event=0x7fff46d75e60, alienWidget=0x2457a70, nativeWidget=0x1c1bff0, buttonDown=<value optimized out>, 
    lastMouseReceiver=<value optimized out>, spontaneous=true) at kernel/qapplication.cpp:2967
#30 0x00007f7c3350603b in QETWidget::translateMouseEvent (this=0x1c1bff0, event=<value optimized out>) at kernel/qapplication_x11.cpp:4380
#31 0x00007f7c335049ac in QApplication::x11ProcessEvent (this=<value optimized out>, event=0x7fff46d765e0) at kernel/qapplication_x11.cpp:3513
#32 0x00007f7c33530552 in x11EventSourceDispatch (s=0x1ac8550, callback=<value optimized out>, user_data=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:146
#33 0x00007f7c2ecb96c2 in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#34 0x00007f7c2ecbd538 in ?? () from /lib/libglib-2.0.so.0
#35 0x00007f7c2ecbd6ec in g_main_context_iteration () from /lib/libglib-2.0.so.0
#36 0x00007f7c34109713 in QEventDispatcherGlib::processEvents (this=0x1a8e1d0, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:412
#37 0x00007f7c3353014e in QGuiEventDispatcherGlib::processEvents (this=0x0, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:204
#38 0x00007f7c340dea82 in QEventLoop::processEvents (this=<value optimized out>, flags=) at kernel/qeventloop.cpp:149
#39 0x00007f7c340dee5c in QEventLoop::exec (this=0x7fff46d76900, flags=) at kernel/qeventloop.cpp:201
#40 0x00007f7c340e3aeb in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1003
#41 0x0000000000428d7b in main (argc=<value optimized out>, argv=<value optimized out>) at ../../ktorrent/main.cpp:173

Reported using DrKonqi