Version:            (using KDE KDE 3.5.7)
Installed from:    Ubuntu Packages

I wanted to file a bug about KMail, but got a hanging Konqueror instead ;)

To reproduce it:
- http://bugs.kde.org/wizard.cgi
- "Continue"
- "KDE 3.5.7" / "Ubuntu Packages"
- "Continue"
- "KMail"
- "Continue"
- <Backspace> / prev. page
- Application version: 1.9.7
- <Enter>
(somehow the kmail selection got lost now - I must select "the Application" again)
- Tried to find KMail (pressing "K" and scrolling in the select box)
- Did not find it easily and wanted to the previous page again: pressed back button
- KMail hangs

I could reproduce it given the recipe above, but was not able to find a smaller testcase that would trigger it.

Backtrace:
0xb5c5c6be in DOM::HTMLGenericFormElementImpl::isFocusable (this=0x9534a48) at /root/kdelibs/kdelibs-3.5.7/./khtml/html/html_formimpl.cpp:946
946     /root/kdelibs/kdelibs-3.5.7/./khtml/html/html_formimpl.cpp: No such file or directory.
        in /root/kdelibs/kdelibs-3.5.7/./khtml/html/html_formimpl.cpp
(gdb) bt
#0  0xb5c5c6be in DOM::HTMLGenericFormElementImpl::isFocusable (this=0x9534a48) at /root/kdelibs/kdelibs-3.5.7/./khtml/html/html_formimpl.cpp:946
#1  0xb5c4ff34 in DOM::NodeImpl::isTabFocusable (this=0x9534a48) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_nodeimpl.h:255
#2  0xb5c295ad in DOM::DocumentImpl::nextFocusNode (this=0x95562f8, fromNode=0x8cef3b0) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_docimpl.cpp:1466
#3  0xb5c18005 in KHTMLView::focusNextPrevNode (this=0x92d0ac0, next=true) at /root/kdelibs/kdelibs-3.5.7/./khtml/khtmlview.cpp:2123
#4  0xb5c187e3 in KHTMLView::focusNextPrevChild (this=0x92d0ac0, next=true) at /root/kdelibs/kdelibs-3.5.7/./khtml/khtmlview.cpp:1772
#5  0xb72b8a7f in QWidget::focusNextPrevChild () from /usr/lib/libqt-mt.so.3
#6  0xb72b8a7f in QWidget::focusNextPrevChild () from /usr/lib/libqt-mt.so.3
#7  0xb72b8a7f in QWidget::focusNextPrevChild () from /usr/lib/libqt-mt.so.3
#8  0xb72b3e0d in QWidget::hide () from /usr/lib/libqt-mt.so.3
#9  0xb7320a93 in QComboBox::hide () from /usr/lib/libqt-mt.so.3
#10 0xb5ce6505 in ~RenderWidget (this=0x92741c8) at /root/kdelibs/kdelibs-3.5.7/./khtml/rendering/render_replaced.cpp:137
#11 0xb5ce6631 in ~RenderFormElement (this=0x92741c8) at /root/kdelibs/kdelibs-3.5.7/./khtml/rendering/render_form.cpp:71
#12 0xb5cfe3a5 in ~RenderSelect (this=0x92741c8) at /root/kdelibs/kdelibs-3.5.7/./khtml/rendering/render_form.h:378
#13 0xb5c90589 in khtml::RenderObject::arenaDelete (this=0xb5e9eac8, arena=0x9463df0, base=0x92741c8) at /root/kdelibs/kdelibs-3.5.7/./khtml/rendering/render_object.cpp:1658
#14 0xb5c905e6 in khtml::RenderObject::arenaDelete (this=0xb5e9eac8, arena=0x9463df0) at /root/kdelibs/kdelibs-3.5.7/./khtml/rendering/render_object.cpp:1671
#15 0xb5cb5a2d in khtml::RenderWidget::deref (this=0xb5e9eac8) at /root/kdelibs/kdelibs-3.5.7/./khtml/rendering/render_replaced.cpp:886
#16 0xb5cb712f in khtml::RenderWidget::detach (this=0x92741c8) at /root/kdelibs/kdelibs-3.5.7/./khtml/rendering/render_replaced.cpp:129
#17 0xb5c2c43c in DOM::NodeImpl::detach (this=0x9542080) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_nodeimpl.cpp:851
#18 0xb5c2c49c in DOM::NodeBaseImpl::detach (this=0x9542080) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_nodeimpl.cpp:1417
#19 0xb5c31847 in DOM::ElementImpl::detach (this=0x9542080) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_elementimpl.cpp:555
#20 0xb5c2c490 in DOM::NodeBaseImpl::detach (this=0x95417d8) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_nodeimpl.cpp:1415
#21 0xb5c31847 in DOM::ElementImpl::detach (this=0x95417d8) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_elementimpl.cpp:555
#22 0xb5c2c490 in DOM::NodeBaseImpl::detach (this=0x9540710) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_nodeimpl.cpp:1415
#23 0xb5c31847 in DOM::ElementImpl::detach (this=0x9540710) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_elementimpl.cpp:555
#24 0xb5c2c490 in DOM::NodeBaseImpl::detach (this=0x9540750) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_nodeimpl.cpp:1415
#25 0xb5c31847 in DOM::ElementImpl::detach (this=0x9540750) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_elementimpl.cpp:555
#26 0xb5c2c490 in DOM::NodeBaseImpl::detach (this=0x9540210) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_nodeimpl.cpp:1415
#27 0xb5c31847 in DOM::ElementImpl::detach (this=0x9540210) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_elementimpl.cpp:555
#28 0xb5c2c490 in DOM::NodeBaseImpl::detach (this=0x9461bf8) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_nodeimpl.cpp:1415
#29 0xb5c31847 in DOM::ElementImpl::detach (this=0x9461bf8) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_elementimpl.cpp:555
#30 0xb5c2c490 in DOM::NodeBaseImpl::detach (this=0x8d1dd58) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_nodeimpl.cpp:1415
#31 0xb5c31847 in DOM::ElementImpl::detach (this=0x8d1dd58) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_elementimpl.cpp:555
#32 0xb5c2c490 in DOM::NodeBaseImpl::detach (this=0x92b08f0) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_nodeimpl.cpp:1415
#33 0xb5c31847 in DOM::ElementImpl::detach (this=0x92b08f0) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_elementimpl.cpp:555
#34 0xb5c2c490 in DOM::NodeBaseImpl::detach (this=0x93aa1b0) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_nodeimpl.cpp:1415
#35 0xb5c31847 in DOM::ElementImpl::detach (this=0x93aa1b0) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_elementimpl.cpp:555
#36 0xb5c2c490 in DOM::NodeBaseImpl::detach (this=0x946e5d0) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_nodeimpl.cpp:1415
#37 0xb5c31847 in DOM::ElementImpl::detach (this=0x946e5d0) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_elementimpl.cpp:555
#38 0xb5c2c490 in DOM::NodeBaseImpl::detach (this=0x944ea40) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_nodeimpl.cpp:1415
#39 0xb5c31847 in DOM::ElementImpl::detach (this=0x944ea40) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_elementimpl.cpp:555
#40 0xb5c2c490 in DOM::NodeBaseImpl::detach (this=0x94606d0) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_nodeimpl.cpp:1415
#41 0xb5c31847 in DOM::ElementImpl::detach (this=0x94606d0) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_elementimpl.cpp:555
#42 0xb5c2c490 in DOM::NodeBaseImpl::detach (this=0x94d8b90) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_nodeimpl.cpp:1415
#43 0xb5c31847 in DOM::ElementImpl::detach (this=0x94d8b90) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_elementimpl.cpp:555
#44 0xb5c2c490 in DOM::NodeBaseImpl::detach (this=0x94636c0) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_nodeimpl.cpp:1415
#45 0xb5c31847 in DOM::ElementImpl::detach (this=0x94636c0) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_elementimpl.cpp:555
#46 0xb5c2c490 in DOM::NodeBaseImpl::detach (this=0x9263440) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_nodeimpl.cpp:1415
#47 0xb5c31847 in DOM::ElementImpl::detach (this=0x9263440) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_elementimpl.cpp:555
#48 0xb5c2c490 in DOM::NodeBaseImpl::detach (this=0x93feb68) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_nodeimpl.cpp:1415
#49 0xb5c31847 in DOM::ElementImpl::detach (this=0x93feb68) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_elementimpl.cpp:555
#50 0xb5c2c490 in DOM::NodeBaseImpl::detach (this=0x93fc388) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_nodeimpl.cpp:1415
#51 0xb5c31847 in DOM::ElementImpl::detach (this=0x93fc388) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_elementimpl.cpp:555
#52 0xb5c2c490 in DOM::NodeBaseImpl::detach (this=0x9556324) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_nodeimpl.cpp:1415
#53 0xb5c32444 in DOM::DocumentImpl::detach (this=0x95562f8) at /root/kdelibs/kdelibs-3.5.7/./khtml/xml/dom_docimpl.cpp:1267
#54 0xb5be1792 in KHTMLPart::clear (this=0x8126b08) at /root/kdelibs/kdelibs-3.5.7/./khtml/khtml_part.cpp:1407
#55 0xb5bfdbe1 in KHTMLPart::restoreState (this=0x8126b08, stream=@0xbf9c7a50) at /root/kdelibs/kdelibs-3.5.7/./khtml/khtml_part.cpp:5566
#56 0xb5bc5a5e in KHTMLPartBrowserExtension::restoreState (this=0x931b328, stream=@0xbf9c7a50) at /root/kdelibs/kdelibs-3.5.7/./khtml/khtml_ext.cpp:105
---Type <return> to continue, or q <return> to quit---
#57 0xb66be587 in KonqView::restoreHistory (this=0x941bdf8) at /root/kdebase/kdebase-3.5.7/./konqueror/konq_view.cc:855
#58 0xb66c503a in KonqView::go (this=0x941bdf8, steps=-1) at /root/kdebase/kdebase-3.5.7/./konqueror/konq_view.cc:825
#59 0xb66d5911 in KonqMainWindow::slotGoHistoryDelayed (this=0x8132890) at /root/kdebase/kdebase-3.5.7/./konqueror/konq_mainwindow.cc:3145
#60 0xb66dd927 in KonqMainWindow::qt_invoke (this=0x8132890, _id=185, _o=0xbf9c7c08) at ./konq_mainwindow.moc:718
#61 0xb727d88b in QObject::activate_signal () from /usr/lib/libqt-mt.so.3
#62 0xb7609ae0 in QSignal::signal () from /usr/lib/libqt-mt.so.3
#63 0xb729d81e in QSignal::activate () from /usr/lib/libqt-mt.so.3
#64 0xb72a5234 in QSingleShotTimer::event () from /usr/lib/libqt-mt.so.3
#65 0xb7214a60 in QApplication::internalNotify () from /usr/lib/libqt-mt.so.3
#66 0xb721688f in QApplication::notify () from /usr/lib/libqt-mt.so.3
#67 0xb791cc32 in KApplication::notify (this=0xbf9c85b8, receiver=0x8ac0528, event=0xbf9c7f58) at /root/kdelibs/kdelibs-3.5.7/./kdecore/kapplication.cpp:550
#68 0xb71a71e9 in QApplication::sendEvent () from /usr/lib/libqt-mt.so.3
#69 0xb72074ab in QEventLoop::activateTimers () from /usr/lib/libqt-mt.so.3
#70 0xb71bbd25 in QEventLoop::processEvents () from /usr/lib/libqt-mt.so.3
#71 0xb722f136 in QEventLoop::enterLoop () from /usr/lib/libqt-mt.so.3
#72 0xb722ef46 in QEventLoop::exec () from /usr/lib/libqt-mt.so.3
#73 0xb7216609 in QApplication::exec () from /usr/lib/libqt-mt.so.3
#74 0xb66da254 in kdemain (argc=4, argv=0x80a7978) at /root/kdebase/kdebase-3.5.7/./konqueror/konq_main.cc:206
#75 0xb7fa4464 in kdeinitmain (argc=4, argv=0x80a7978) at konqueror_dummy.cc:3
#76 0x0804e6bf in launch (argc=4, _name=0x808d66c "konqueror", args=0x808d69d "", cwd=0x808d69e "/home/daniel", envc=31, envs=0x808dacc "", reset_env=true, tty=0x0, avoid_loops=false,
    startup_id_str=0x808dad1 "base;1180565848;261031;7422_TIME160881326") at /root/kdelibs/kdelibs-3.5.7/./kinit/kinit.cpp:673
#77 0x0804ef42 in handle_launcher_request (sock=5) at /root/kdelibs/kdelibs-3.5.7/./kinit/kinit.cpp:1240
#78 0x0804f4b1 in handle_requests (waitForPid=0) at /root/kdelibs/kdelibs-3.5.7/./kinit/kinit.cpp:1433
#79 0x080505ac in main (argc=5, argv=0xbf9c8d44, envp=0xbf9c8d5c) at /root/kdelibs/kdelibs-3.5.7/./kinit/kinit.cpp:1909
#80 0xb7d06ebc in __libc_start_main () from /lib/tls/i686/cmov/libc.so.6
#81 0x0804bb51 in _start ()

Kubuntu Feisty / KDE 3.5.7