What are your KDE4/Qt4 versions (or SVN revision/branch)?
When are you experiencing this crash? On a fresh-start, when resuming ?
There are some related reports : bug 182072 / bug 180428
If you can reproduce the crash at will, may you read http://techbase.kde.org/Development/Tutorials/Debugging/How_to_create_useful_crash_reports and post a complete backtrace here? Thanks :)

Sorry, but I won't be able to reproduce that, cause I switched back to stable KDE (4.2). This was happening on recent SVN snapshot of whole KDE (compiled about 2 days ago). This might have been related to problems with gadu-gadu protocol (#184696), but unfortunately no one ever looked into that bug.

The crash seems to be related to the Yahoo protocol and (may be) to the NowPlaying plugin. Please reopen this bug report if you experience this again. Thanks

We have received a Yahoo/NowPlaying crash over at Launchpad: https://launchpad.net/bugs/348661

Using: Qt 4.5.0, KDE 4.2.1.
The user said that Kopete was offline when he got the crash notification, but the crash notification could have been delayed... The backtrace seems to suggest that the Yahoo status was being changed to "away" when the crash happened.

Here's the backtrace:
#0  0xb304c776 in ClientStream::cp_outgoingData (this=0xa6498d8, 
    outgoingBytes=@0xbf86dbf0)
    at /build/buildd/kdenetwork-4.2.1/kopete/protocols/yahoo/libkyahoo/yahooclientstream.cpp:302
	__PRETTY_FUNCTION__ = "void ClientStream::cp_outgoingData(const QByteArray&)"
#1  0xb304e2bd in ClientStream::qt_metacall (this=0xa6498d8, 
    _c=QMetaObject::InvokeMetaMethod, _id=8, _a=0xbf86db9c)
    at /build/buildd/kdenetwork-4.2.1/obj-i486-linux-gnu/kopete/protocols/yahoo/libkyahoo/yahooclientstream.moc:100
No locals.
#2  0xb6da3cb8 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#3  0xb6da4942 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#4  0xb3052d23 in CoreProtocol::outgoingData (this=0xb0a1db8, _t1=@0xbf86dbf0)
    at /build/buildd/kdenetwork-4.2.1/obj-i486-linux-gnu/kopete/protocols/yahoo/libkyahoo/coreprotocol.moc:85
	_a = {0x0, 0xbf86dbf0}
#5  0xb3054647 in CoreProtocol::outgoingTransfer (this=0xb0a1db8, 
    outgoing=0xbc7cac8)
    at /build/buildd/kdenetwork-4.2.1/kopete/protocols/yahoo/libkyahoo/coreprotocol.cpp:141
	bytesOut = {static shared_null = {ref = {_q_value = 4789}, alloc = 0, 
    size = 0, data = 0x80bb6d8 "", array = ""}, static shared_empty = {ref = {
      _q_value = 57}, alloc = 0, size = 0, data = 0xb6e82998 "", array = ""}, 
  d = 0xa28d9e0}
	__PRETTY_FUNCTION__ = "void CoreProtocol::outgoingTransfer(Transfer*)"
#6  0xb304d86e in ClientStream::write (this=0xa6498d8, request=0xbc7cac8)
    at /build/buildd/kdenetwork-4.2.1/kopete/protocols/yahoo/libkyahoo/yahooclientstream.cpp:252
	__PRETTY_FUNCTION__ = "virtual void ClientStream::write(Transfer*)"
#7  0xb303f601 in Client::send (this=0x9f91030, request=0xbc7cac8)
    at /build/buildd/kdenetwork-4.2.1/kopete/protocols/yahoo/libkyahoo/client.cpp:823
	__PRETTY_FUNCTION__ = "void Client::send(Transfer*)"
#8  0xb304390a in Task::send (this=0x9db28f0, request=0xbc7cac8)
    at /build/buildd/kdenetwork-4.2.1/kopete/protocols/yahoo/libkyahoo/task.cpp:178
No locals.
#9  0xb305f3cf in ChangeStatusTask::onGo (this=0x9db28f0)
    at /build/buildd/kdenetwork-4.2.1/kopete/protocols/yahoo/libkyahoo/changestatustask.cpp:56
	t = (class YMSGTransfer *) 0xbc7cac8
	__PRETTY_FUNCTION__ = "virtual void ChangeStatusTask::onGo()"
#10 0xb304372a in Task::go (this=0x9db28f0, autoDelete=true)
    at /build/buildd/kdenetwork-4.2.1/kopete/protocols/yahoo/libkyahoo/task.cpp:122
No locals.
#11 0xb3040be3 in Client::changeStatus (this=0x9f91030, status=555, 
    message=@0xbf86dd94, type=Yahoo::StatusTypeAway)
    at /build/buildd/kdenetwork-4.2.1/kopete/protocols/yahoo/libkyahoo/client.cpp:416
	__PRETTY_FUNCTION__ = "void Client::changeStatus(Yahoo::Status, const QString&, Yahoo::StatusType)"
#12 0xb3112139 in YahooAccount::setStatusMessage (this=0x9f90a00, 
    statusMessage=@0xbf86deb0)
    at /build/buildd/kdenetwork-4.2.1/kopete/protocols/yahoo/yahooaccount.cpp:1894
No locals.
#13 0xb314f162 in NowListeningPlugin::slotAdvertCurrentMusic (this=0x9f95dc0)
    at /build/buildd/kdenetwork-4.2.1/kopete/plugins/nowlistening/nowlisteningplugin.cpp:296
	tmpStatusMessage = {d = {d = 0x9df0e08}}
	currentStatusMessage = {d = {d = 0x9b7c3d8}}
	a = (class Kopete::Account *) 0x9f90a00
	_container_ = {c = {{p = {static shared_null = {ref = {
            _q_value = 30441}, alloc = 0, begin = 0, end = 0, sharable = 1, 
          array = {0x0}}, d = 0xa2f8558}, d = 0xa2f8558}}, brk = 0, i = {
    i = 0xa2f856c}, e = {i = 0xa2f8578}}
	advert = {static null = {<No data fields>}, static shared_null = {
    ref = {_q_value = 26766}, alloc = 0, size = 0, data = 0x80bb61a, 
    clean = 0, simpletext = 0, righttoleft = 0, asciiCache = 0, capacity = 0, 
    reserved = 0, array = {0}}, static shared_empty = {ref = {
      _q_value = 346}, alloc = 0, size = 0, data = 0xb6e82a6e, clean = 0, 
    simpletext = 0, righttoleft = 0, asciiCache = 1, capacity = 0, 
    reserved = 0, array = {0}}, d = 0x80bb608, 
  static codecForCStrings = 0x9954468}
	track = {static null = {<No data fields>}, static shared_null = {
    ref = {_q_value = 26766}, alloc = 0, size = 0, data = 0x80bb61a, 
    clean = 0, simpletext = 0, righttoleft = 0, asciiCache = 0, capacity = 0, 
    reserved = 0, array = {0}}, static shared_empty = {ref = {
      _q_value = 346}, alloc = 0, size = 0, data = 0xb6e82a6e, clean = 0, 
    simpletext = 0, righttoleft = 0, asciiCache = 1, capacity = 0, 
    reserved = 0, array = {0}}, d = 0x9c4eee8, 
  static codecForCStrings = 0x9954468}
	album = {static null = {<No data fields>}, static shared_null = {
    ref = {_q_value = 26766}, alloc = 0, size = 0, data = 0x80bb61a, 
    clean = 0, simpletext = 0, righttoleft = 0, asciiCache = 0, capacity = 0, 
    reserved = 0, array = {0}}, static shared_empty = {ref = {
      _q_value = 346}, alloc = 0, size = 0, data = 0xb6e82a6e, clean = 0, 
    simpletext = 0, righttoleft = 0, asciiCache = 1, capacity = 0, 
    reserved = 0, array = {0}}, d = 0xb6e82a5c, 
  static codecForCStrings = 0x9954468}
	accountsList = {{p = {static shared_null = {ref = {_q_value = 30441}, 
        alloc = 0, begin = 0, end = 0, sharable = 1, array = {0x0}}, 
      d = 0xa2f8558}, d = 0xa2f8558}}
	artist = {static null = {<No data fields>}, static shared_null = {
    ref = {_q_value = 26766}, alloc = 0, size = 0, data = 0x80bb61a, 
    clean = 0, simpletext = 0, righttoleft = 0, asciiCache = 0, capacity = 0, 
    reserved = 0, array = {0}}, static shared_empty = {ref = {
      _q_value = 346}, alloc = 0, size = 0, data = 0xb6e82a6e, clean = 0, 
    simpletext = 0, righttoleft = 0, asciiCache = 1, capacity = 0, 
    reserved = 0, array = {0}}, d = 0xb6e82a5c, 
  static codecForCStrings = 0x9954468}
	isPlaying = true
#14 0xb314ffcb in NowListeningPlugin::qt_metacall (this=0x9f95dc0, 
    _c=QMetaObject::InvokeMetaMethod, _id=2, _a=0xbf86df98)
    at /build/buildd/kdenetwork-4.2.1/obj-i486-linux-gnu/kopete/plugins/nowlistening/nowlisteningplugin.moc:79
No locals.
#15 0xb6da3cb8 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#16 0xb6da4942 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#17 0xb6ddf727 in QTimer::timeout () from /usr/lib/libQtCore.so.4
#18 0xb6da970e in QTimer::timerEvent () from /usr/lib/libQtCore.so.4
#19 0xb6d9e16f in QObject::event () from /usr/lib/libQtCore.so.4
#20 0xb633ff5c in QApplicationPrivate::notify_helper ()
   from /usr/lib/libQtGui.so.4
#21 0xb634825e in QApplication::notify () from /usr/lib/libQtGui.so.4
#22 0xb72db70d in KApplication::notify (this=0xbf86e6ac, receiver=0x9963530, 
    event=0xbf86e41c)
    at /build/buildd/kde4libs-4.2.1a/kdeui/kernel/kapplication.cpp:307
No locals.
#23 0xb6d8da4b in QCoreApplication::notifyInternal ()
   from /usr/lib/libQtCore.so.4
#24 0xb6dbcd81 in ?? () from /usr/lib/libQtCore.so.4
#25 0xb6db94f0 in ?? () from /usr/lib/libQtCore.so.4
#26 0xb5aeba58 in IA__g_main_context_dispatch (context=0x996b290)
    at /build/buildd/glib2.0-2.20.0/glib/gmain.c:1814
No locals.
#27 0xb5aeefbb in g_main_context_iterate (context=0x996b290, block=1, 
    dispatch=1, self=0x996dc08)
    at /build/buildd/glib2.0-2.20.0/glib/gmain.c:2448
	max_priority = 0
	timeout = 0
	some_ready = 1
	nfds = 8
	allocated_nfds = <value optimized out>
	fds = (GPollFD *) 0xbb02e98
	__PRETTY_FUNCTION__ = "g_main_context_iterate"
#28 0xb5aef138 in IA__g_main_context_iteration (context=0x996b290, 
    may_block=1) at /build/buildd/glib2.0-2.20.0/glib/gmain.c:2511
	retval = <value optimized out>
#29 0xb6db9448 in QEventDispatcherGlib::processEvents ()
   from /usr/lib/libQtCore.so.4
#30 0xb63e1425 in ?? () from /usr/lib/libQtGui.so.4
#31 0xb6d8c07a in QEventLoop::processEvents () from /usr/lib/libQtCore.so.4
#32 0xb6d8c4ba in QEventLoop::exec () from /usr/lib/libQtCore.so.4
#33 0xb6d8e969 in QCoreApplication::exec () from /usr/lib/libQtCore.so.4
#34 0xb633fdd7 in QApplication::exec () from /usr/lib/libQtGui.so.4
#35 0x0808c2af in main (argc=3, argv=0xbf86ea94)
    at /build/buildd/kdenetwork-4.2.1/kopete/kopete/main.cpp:102
	aboutData = {d = 0x9950328}
	options = {d = 0x995c118}
	kopete = {<KUniqueApplication> = {<KApplication> = {<> = {<No data fields>}, static staticMetaObject = {d = {superdata = 0xb6bcd108, 
          stringdata = 0xb74550e0 "KApplication", data = 0xb7455280, 
          extradata = 0x0}}, static loadedByKdeinit = false, 
      static KApp = 0xbf86e6ac, d = 0x99adc18}, static staticMetaObject = {
      d = {superdata = 0xb747cca0, 
        stringdata = 0xb7455aa0 "KUniqueApplication", data = 0xb7455ba0, 
        extradata = 0x0}}, d = 0x99f64c0}, static staticMetaObject = {d = {
      superdata = 0x80bb758, stringdata = 0x80aeec0 "KopeteApplication", 
      data = 0x80af000, extradata = 0x0}}, m_mainWindow = {o = 0x99f1f70}, 
  m_isShuttingDown = false, m_emoticonHandler = 0x9b77a80, 
  m_fileEngineHandler = 0x9b77ba8}

*** Bug 206088 has been marked as a duplicate of this bug. ***

Bug 209118 got an updated and complete backtrace

*** Bug 209118 has been marked as a duplicate of this bug. ***

SVN commit 1044526 by rjarosz:

Disconnect signals on reset so we don't get signals twice on reconnect.
Check if d->bs is not null.

BUG: 188042


 M  +4 -0      yahooclientstream.cpp  


WebSVN link: http://websvn.kde.org/?view=rev&revision=1044526

*** Bug 193760 has been marked as a duplicate of this bug. ***

*** Bug 197488 has been marked as a duplicate of this bug. ***

*** Bug 207247 has been marked as a duplicate of this bug. ***

*** Bug 208019 has been marked as a duplicate of this bug. ***

*** Bug 212601 has been marked as a duplicate of this bug. ***

SVN commit 1044534 by rjarosz:

Backport commit 1044526.
Disconnect signals on reset so we don't get signals twice on reconnect.
Check if d->bs is not null.

CCBUG: 188042



 M  +4 -0      yahooclientstream.cpp  


WebSVN link: http://websvn.kde.org/?view=rev&revision=1044534

*** Bug 213055 has been marked as a duplicate of this bug. ***

*** Bug 213487 has been marked as a duplicate of this bug. ***

*** Bug 215064 has been marked as a duplicate of this bug. ***

*** Bug 215979 has been marked as a duplicate of this bug. ***

*** Bug 218105 has been marked as a duplicate of this bug. ***

*** Bug 217837 has been marked as a duplicate of this bug. ***

*** Bug 218640 has been marked as a duplicate of this bug. ***

*** Bug 219838 has been marked as a duplicate of this bug. ***

*** Bug 224184 has been marked as a duplicate of this bug. ***