Application that crashed: kate
Version of the application: 3.3.5
KDE Version: 4.3.5 (KDE 4.3.5)
Qt Version: 4.5.2
Operating System: Linux 2.6.31-17-generic x86_64
Distribution: Ubuntu 9.10

What I was doing when the application crashed:
Several source text files had been opened in kate. After updating the files by an external application (git), kate has correctly reported that the files had been modified (red icon before each file name in the list). After trying to save some of the contents stored in kate (by overwriting the files modified by git), kate crashed.

 -- Backtrace:
Application: Kate (kate), signal: Segmentation fault
[KCrash Handler]
#5  QString::size (this=<value optimized out>, other=...) at ../../include/QtCore/../../src/corelib/tools/qstring.h:104
#6  QString::operator== (this=<value optimized out>, other=...) at tools/qstring.cpp:1912
#7  0x00007f1f20ad506b in ?? () from /usr/lib/libkio.so.5
#8  0x00007f1f20ad66c4 in ?? () from /usr/lib/libkio.so.5
#9  0x00007f1f24a3bddc in QMetaObject::activate (sender=0x23d6820, from_signal_index=<value optimized out>, to_signal_index=<value optimized out>, argv=0xc) at kernel/qobject.cpp:3113
#10 0x00007f1f24a71e9e in QSocketNotifier::activated (this=0xffffffc024d10000, _t1=11) at .moc/release-shared/moc_qsocketnotifier.cpp:83
#11 0x00007f1f24a40773 in QSocketNotifier::event (this=0x23d6820, e=0x7fff83032ba0) at kernel/qsocketnotifier.cpp:316
#12 0x00007f1f25e6defc in QApplicationPrivate::notify_helper (this=0x2393e70, receiver=0x23d6820, e=0x7fff83032ba0) at kernel/qapplication.cpp:4056
#13 0x00007f1f25e751ce in QApplication::notify (this=0x7fff83032f00, receiver=0x23d6820, e=0x7fff83032ba0) at kernel/qapplication.cpp:4021
#14 0x00007f1f251adf46 in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#15 0x00007f1f24a26c2c in QCoreApplication::notifyInternal (this=0x7fff83032f00, receiver=0x23d6820, event=0x7fff83032ba0) at kernel/qcoreapplication.cpp:610
#16 0x00007f1f24a4f42a in QCoreApplication::sendEvent (source=0x2397990) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:213
#17 socketNotifierSourceDispatch (source=0x2397990) at kernel/qeventdispatcher_glib.cpp:110
#18 0x00007f1f233ffbce in g_main_dispatch (context=0x2396920) at /build/buildd/glib2.0-2.22.3/glib/gmain.c:1960
#19 IA__g_main_context_dispatch (context=0x2396920) at /build/buildd/glib2.0-2.22.3/glib/gmain.c:2513
#20 0x00007f1f23403598 in g_main_context_iterate (context=0x2396920, block=<value optimized out>, dispatch=<value optimized out>, self=<value optimized out>)
    at /build/buildd/glib2.0-2.22.3/glib/gmain.c:2591
#21 0x00007f1f234036c0 in IA__g_main_context_iteration (context=0x2396920, may_block=1) at /build/buildd/glib2.0-2.22.3/glib/gmain.c:2654
#22 0x00007f1f24a4f1a6 in QEventDispatcherGlib::processEvents (this=0x2376c80, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:327
#23 0x00007f1f25f024be in QGuiEventDispatcherGlib::processEvents (this=0xffffffc024d10000, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:202
#24 0x00007f1f24a25532 in QEventLoop::processEvents (this=<value optimized out>, flags=) at kernel/qeventloop.cpp:149
#25 0x00007f1f24a25904 in QEventLoop::exec (this=0x7fff83032e00, flags=) at kernel/qeventloop.cpp:201
#26 0x00007f1f24a27ab9 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#27 0x00007f1f26bf4d2d in kdemain () from /usr/lib/libkdeinit4_kate.so
#28 0x00007f1f2689fabd in __libc_start_main (main=<value optimized out>, argc=<value optimized out>, ubp_av=<value optimized out>, init=<value optimized out>, fini=<value optimized out>, 
    rtld_fini=<value optimized out>, stack_end=0x7fff83034118) at libc-start.c:220
#29 0x0000000000400679 in _start ()

Reported using DrKonqi