Version:            (using KDE KDE 3.2.1)
Installed from:    Debian testing/unstable Packages

One example to reliably reprodruce the bug:

Visit http://demo.otrs.org/otrs/index.pl, login, choose a queue with tickets, click "Note" in a tickets action bar, leave the text box blank and click submit. A popup will inform you that you should have entered a message, clicking ok crashes Konqueror with the following backtrace.
I noticed this bug on several other sites as well.

#0  0x4cf1abd8 in waitpid () from /lib/libpthread.so.0
#1  0x407f3b78 in ?? () from /usr/lib/libkdecore.so.4
#2  0x40724f54 in KCrash::defaultCrashHandler () from /usr/lib/libkdecore.so.4
#3  0x4cf19815 in __pthread_sighandler () from /lib/libpthread.so.0
#4  <signal handler called>
#5  0x4b645867 in QObject::inherits () from /usr/lib/libqt-mt.so.3
#6  0x413b9b79 in KHTMLPartBrowserExtension::updateEditActions ()
   from /usr/lib/libkhtml.so.4
#7  0x413b92ea in KHTMLPartBrowserExtension::editableWidgetFocused ()
   from /usr/lib/libkhtml.so.4
#8  0x4140cd1c in DOM::removeForbidden () from /usr/lib/libkhtml.so.4
#9  0x413d79ce in KStaticDeleter<KHTMLPageCache>::~KStaticDeleter ()
   from /usr/lib/libkhtml.so.4
#10 0x413d7752 in KStaticDeleter<KHTMLPageCache>::~KStaticDeleter ()
   from /usr/lib/libkhtml.so.4
#11 0x413d7f6f in KStaticDeleter<KHTMLPageCache>::~KStaticDeleter ()
   from /usr/lib/libkhtml.so.4
#12 0x413d42e4 in KStaticDeleter<KHTMLPageCache>::~KStaticDeleter ()
   from /usr/lib/libkhtml.so.4
#13 0x41414fb9 in DOM::removeForbidden () from /usr/lib/libkhtml.so.4
#14 0x4153955d in DOM::HTMLTextAreaElement::focus ()
   from /usr/lib/libkhtml.so.4
#15 0x414bb8ef in QPtrDict<khtml::CachedObjectClient>::deleteItem ()
   from /usr/lib/libkhtml.so.4
#16 0x41498597 in QPtrDict<khtml::CachedObjectClient>::deleteItem ()
   from /usr/lib/libkhtml.so.4
#17 0x416092e0 in KJS::Object::call () from /usr/lib/libkjs.so.1
#18 0x415db44d in KJS::roundValue () from /usr/lib/libkjs.so.1
#19 0x415dfb2a in KJS::roundValue () from /usr/lib/libkjs.so.1
#20 0x415e64bc in KJS::roundValue () from /usr/lib/libkjs.so.1
#21 0x415df93f in KJS::roundValue () from /usr/lib/libkjs.so.1
#22 0x415dfece in KJS::roundValue () from /usr/lib/libkjs.so.1
#23 0x415dfeaa in KJS::roundValue () from /usr/lib/libkjs.so.1
#24 0x415e6446 in KJS::roundValue () from /usr/lib/libkjs.so.1
#25 0x415df93f in KJS::roundValue () from /usr/lib/libkjs.so.1
#26 0x415e5993 in KJS::roundValue () from /usr/lib/libkjs.so.1
#27 0x41604a0c in KJS::DeclaredFunctionImp::execute ()
   from /usr/lib/libkjs.so.1
#28 0x41603de2 in KJS::FunctionImp::call () from /usr/lib/libkjs.so.1
#29 0x416092e0 in KJS::Object::call () from /usr/lib/libkjs.so.1
#30 0x415db44d in KJS::roundValue () from /usr/lib/libkjs.so.1
#31 0x415e2d0e in KJS::roundValue () from /usr/lib/libkjs.so.1
#32 0x415e6446 in KJS::roundValue () from /usr/lib/libkjs.so.1
#33 0x415df93f in KJS::roundValue () from /usr/lib/libkjs.so.1
#34 0x415e5993 in KJS::roundValue () from /usr/lib/libkjs.so.1
#35 0x41604a0c in KJS::DeclaredFunctionImp::execute ()
   from /usr/lib/libkjs.so.1
#36 0x41603de2 in KJS::FunctionImp::call () from /usr/lib/libkjs.so.1
#37 0x416092e0 in KJS::Object::call () from /usr/lib/libkjs.so.1
#38 0x414ec2c0 in TestFunctionImp::call () from /usr/lib/libkhtml.so.4
#39 0x413d8293 in KStaticDeleter<KHTMLPageCache>::~KStaticDeleter ()
   from /usr/lib/libkhtml.so.4
#40 0x413d790b in KStaticDeleter<KHTMLPageCache>::~KStaticDeleter ()
   from /usr/lib/libkhtml.so.4
#41 0x413d7752 in KStaticDeleter<KHTMLPageCache>::~KStaticDeleter ()
   from /usr/lib/libkhtml.so.4
#42 0x4138b581 in KHTMLView::dispatchMouseEvent () from /usr/lib/libkhtml.so.4
#43 0x41386edd in KHTMLView::viewportMouseReleaseEvent ()
   from /usr/lib/libkhtml.so.4
#44 0x413880f6 in KHTMLView::eventFilter () from /usr/lib/libkhtml.so.4
#45 0x4b645c4e in QObject::activate_filters () from /usr/lib/libqt-mt.so.3
#46 0x4b645b7c in QObject::event () from /usr/lib/libqt-mt.so.3
#47 0x4b67d03f in QWidget::event () from /usr/lib/libqt-mt.so.3
#48 0x4b5ec79f in QApplication::internalNotify () from /usr/lib/libqt-mt.so.3
#49 0x4b5ebea1 in QApplication::notify () from /usr/lib/libqt-mt.so.3
#50 0x406a29ed in KApplication::notify () from /usr/lib/libkdecore.so.4
#51 0x4b584608 in QETWidget::translateMouseEvent () from /usr/lib/libqt-mt.so.3
#52 0x4b582132 in QApplication::x11ProcessEvent () from /usr/lib/libqt-mt.so.3
#53 0x4b598221 in QEventLoop::processEvents () from /usr/lib/libqt-mt.so.3
#54 0x4b600008 in QEventLoop::enterLoop () from /usr/lib/libqt-mt.so.3
#55 0x4b5ffeb8 in QEventLoop::exec () from /usr/lib/libqt-mt.so.3
#56 0x4b5ec9f1 in QApplication::exec () from /usr/lib/libqt-mt.so.3
#57 0x40c54c2c in kdemain () from /usr/lib/libkdeinit_konqueror.so
#58 0x40001866 in kdeinitmain () from /usr/lib/kde3/konqueror.so

Greetings,

  Gunter Ohrner