Version:            (using KDE Devel)
Installed from:    Compiled sources
Compiler:          g++ (GCC) 4.1.3 20070306 (prerelease) (Debian 4.1.2-2) 
OS:                Linux

This is what I did:
- latest svn checkout (3.5 branch) + official debian qt package (version 3:3.3.7-3)
- kdelibs and kdebase compiled with --enable-debug
- start konqueror in default configuration (rm -r ~/.kde)
- ctrl-shift-n for new tab
- load anything (webpage or local directory)
- hold "win"-key pressed and press "ctrl-w" to close the tab
=> crash with appended backtrace

If the page is kept blank or closed with the mouse, no crash occurs.
The crash occurs before any key is released.

Using host libthread_db library "/lib/libthread_db.so.1".
[Thread debugging using libthread_db enabled]
[New Thread -1234143536 (LWP 14156)]
[KCrash handler]
#5  0x00000000 in ?? ()
#6  0xb6f7b640 in qt_inheritedBy () from /usr/share/qt3/lib/libqt-mt.so.3
#7  0xb766224c in qt_cast<QLineEdit*> (object=0x847cce0)
    at /usr/share/qt3/include/qobjectdefs.h:173
#8  0xb765bd9b in KApplication::notify (this=0xbfe4c5f4, receiver=0x847cce0, 
    event=0xbfe4c100) at /home/kde/src/3.5/kdelibs/kdecore/kapplication.cpp:460
#9  0xb6ea8495 in QApplication::sendSpontaneousEvent ()
   from /usr/share/qt3/lib/libqt-mt.so.3
#10 0xb6e996f9 in QETWidget::translateKeyEvent ()
   from /usr/share/qt3/lib/libqt-mt.so.3
#11 0xb6ea5723 in QApplication::x11ProcessEvent ()
   from /usr/share/qt3/lib/libqt-mt.so.3
#12 0xb6ebbd02 in QEventLoop::processEvents ()
   from /usr/share/qt3/lib/libqt-mt.so.3
#13 0xb6f2f179 in QEventLoop::enterLoop ()
   from /usr/share/qt3/lib/libqt-mt.so.3
#14 0xb6f2ef9a in QEventLoop::exec () from /usr/share/qt3/lib/libqt-mt.so.3
#15 0xb6f167bf in QApplication::exec () from /usr/share/qt3/lib/libqt-mt.so.3
#16 0xb63cadec in kdemain (argc=2, argv=0x807a8e0)
    at /home/kde/src/3.5/kdebase/konqueror/konq_main.cc:206
#17 0xb74fd690 in kdeinitmain (argc=2, argv=0x807a8e0) at konqueror_dummy.cc:3
#18 0x0805039b in launch (argc=2, _name=0x80782e4 "konqueror", 
    args=0x80782f7 "\001", cwd=0x0, envc=1, envs=0x8078309 "", 
    reset_env=false, tty=0x0, avoid_loops=false, 
    startup_id_str=0x807830d "c027;1173524918;923081;30030_TIME998847018")
    at /home/kde/src/3.5/kdelibs/kinit/kinit.cpp:673
#19 0x08050ccd in handle_launcher_request (sock=9)
    at /home/kde/src/3.5/kdelibs/kinit/kinit.cpp:1240
#20 0x0805142c in handle_requests (waitForPid=0)
    at /home/kde/src/3.5/kdelibs/kinit/kinit.cpp:1443
#21 0x08051f3f in main (argc=5, argv=0xbfe4d0c4, envp=0xbfe4d0dc)
    at /home/kde/src/3.5/kdelibs/kinit/kinit.cpp:1909