Version:            (using KDE Devel)
Installed from:    Compiled sources
Compiler:          gcc version 3.2.3 
OS:          Linux

This crash occurs when all the slider have been removed from the mixer applet.  Then when you bring up the configuration widget and click ok or apply, the applet crashes with signal 11.  The problem appears to be in KMixApplet::applyPreferences (kmixapplet.cpp:504)
where m_mixerWidget is being deref'ed but it is null when there are no sliders.

backtrace:

[New Thread 16384 (LWP 3892)]
0x413775c9 in waitpid () from /lib/libpthread.so.0
#0  0x413775c9 in waitpid () from /lib/libpthread.so.0
#1  0x407d710c in KCrash::defaultCrashHandler(int) (sig=11) at kcrash.cpp:246
#2  0x41375c45 in __pthread_sighandler () from /lib/libpthread.so.0
#3  <signal handler called>
#4  0x402de9e2 in QRect::size() const (this=0x0) at qrect.h:254
#5  0x402de4cc in QWidget::size() const (this=0x0) at qwidget.h:743
#6  0x41766fa4 in KMixApplet::applyPreferences() (this=0x80cb640)
    at kmixapplet.cpp:515
#7  0x417674d9 in KMixApplet::qt_invoke(int, QUObject*) (this=0x80cb640, 
    _id=48, _o=0xbfffe850) at kmixapplet.moc:193
#8  0x40c42c95 in QObject::activate_signal(QConnectionList*, QUObject*) (
    this=0x80f7b90, clist=0x80fe0f8, o=0xbfffe850) at kernel/qobject.cpp:2359
#9  0x40c42b34 in QObject::activate_signal(int) (this=0x80f7b90, signal=21)
    at kernel/qobject.cpp:2328
#10 0x417671da in AppletConfigDialog::applied() (this=0x80f7b90)
    at kmixapplet.moc:88
#11 0x417643cb in AppletConfigDialog::slotApply() (this=0x80f7b90)
    at kmixapplet.cpp:102
#12 0x4176439d in AppletConfigDialog::slotOk() (this=0x80f7b90)
    at kmixapplet.cpp:96
#13 0x40579179 in KDialogBase::qt_invoke(int, QUObject*) (this=0x80f7b90, 
    _id=73, _o=0xbfffe990) at kdialogbase.moc:359
#14 0x4176725e in AppletConfigDialog::qt_invoke(int, QUObject*) (
    this=0x80f7b90, _id=73, _o=0xbfffe990) at kmixapplet.moc:97
#15 0x40c42c95 in QObject::activate_signal(QConnectionList*, QUObject*) (
    this=0x80f9920, clist=0x80f98f8, o=0xbfffe990) at kernel/qobject.cpp:2359
#16 0x40c42b34 in QObject::activate_signal(int) (this=0x80f9920, signal=4)
    at kernel/qobject.cpp:2328
#17 0x40f9f035 in QButton::clicked() (this=0x80f9920)
    at .moc/debug-shared-mt/moc_qbutton.cpp:152
#18 0x40cd75ef in QButton::mouseReleaseEvent(QMouseEvent*) (this=0x80f9920, 
    e=0xbfffed30) at widgets/qbutton.cpp:832
#19 0x40c7a6d7 in QWidget::event(QEvent*) (this=0x80f9920, e=0xbfffed30)
    at kernel/qwidget.cpp:4648
#20 0x40be06cb in QApplication::internalNotify(QObject*, QEvent*) (
    this=0xbffff2b0, receiver=0x80f9920, e=0xbfffed30)
    at kernel/qapplication.cpp:2614
#21 0x40bdfe81 in QApplication::notify(QObject*, QEvent*) (this=0xbffff2b0, 
    receiver=0x80f9920, e=0xbfffed30) at kernel/qapplication.cpp:2400
#22 0x4074c57c in KApplication::notify(QObject*, QEvent*) (this=0xbffff2b0, 
    receiver=0x80f9920, event=0xbfffed30) at kapplication.cpp:503
#23 0x40b767f1 in QApplication::sendSpontaneousEvent(QObject*, QEvent*) (
    receiver=0x80f9920, event=0xbfffed30) at qapplication.h:493
#24 0x40b6f8a3 in QETWidget::translateMouseEvent(_XEvent const*) (
    this=0x80f9920, event=0xbffff0c0) at kernel/qapplication_x11.cpp:4224
#25 0x40b6d509 in QApplication::x11ProcessEvent(_XEvent*) (this=0xbffff2b0, 
    event=0xbffff0c0) at kernel/qapplication_x11.cpp:3387
#26 0x40b88002 in QEventLoop::processEvents(unsigned) (this=0x808e540, flags=4)
    at kernel/qeventloop_x11.cpp:192
#27 0x40bf4942 in QEventLoop::enterLoop() (this=0x808e540)
    at kernel/qeventloop.cpp:198
#28 0x40bf485e in QEventLoop::exec() (this=0x808e540)
    at kernel/qeventloop.cpp:145
#29 0x40be084f in QApplication::exec() (this=0xbffff2b0)
    at kernel/qapplication.cpp:2737
#30 0x416c7312 in kdemain () from /opt/kde/lib/libkdeinit_appletproxy.so