Application: kmix (4)
KDE Platform Version: 4.8.1 (4.8.1)
Qt Version: 4.8.0
Operating System: Linux 3.2.0-18-generic x86_64
Distribution: Ubuntu 11.10

-- Information about the crash:
Veromix is also installed. 
Machine: ASUS G73SW (laptop)
As an aside (don't know if it is intended), KDE starts with the audio muted whatever it was its status on shutdown. 
Thanks for the great work!

The crash can be reproduced every time.

-- Backtrace:
Application: KMix (kmix), signal: Segmentation fault
[Current thread is 1 (Thread 0x7f7b40c3f7c0 (LWP 3004))]

Thread 3 (Thread 0x7f7b1f73a700 (LWP 3012)):
#0  0x00007f7b371c11fd in __pthread_mutex_unlock_usercnt (mutex=<optimized out>, decr=<optimized out>) at pthread_mutex_unlock.c:52
#1  __pthread_mutex_unlock (mutex=0x1147608) at pthread_mutex_unlock.c:290
#2  0x00007f7b36652fe4 in g_main_context_prepare () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007f7b36653dfd in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007f7b36654429 in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#5  0x00007f7b3d2c8c06 in QEventDispatcherGlib::processEvents (this=0x1336f30, flags=<optimized out>) at kernel/qeventdispatcher_glib.cpp:426
#6  0x00007f7b3d2983e2 in QEventLoop::processEvents (this=<optimized out>, flags=...) at kernel/qeventloop.cpp:149
#7  0x00007f7b3d298637 in QEventLoop::exec (this=0x7f7b1f739cd0, flags=...) at kernel/qeventloop.cpp:204
#8  0x00007f7b3d198067 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:501
#9  0x00007f7b3d27817f in QInotifyFileSystemWatcherEngine::run (this=0x14cbcd0) at io/qfilesystemwatcher_inotify.cpp:248
#10 0x00007f7b3d19b08b in QThreadPrivate::start (arg=0x14cbcd0) at thread/qthread_unix.cpp:298
#11 0x00007f7b3259f354 in ?? () from /usr/lib/libGL.so.1
#12 0x00007f7b371bdefc in start_thread (arg=0x7f7b1f73a700) at pthread_create.c:304
#13 0x00007f7b4052759d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#14 0x0000000000000000 in ?? ()

Thread 2 (Thread 0x7f7b1ed2e700 (LWP 3062)):
#0  0x00007f7b4051b473 in __GI___poll (fds=<optimized out>, nfds=<optimized out>, timeout=<optimized out>) at ../sysdeps/unix/sysv/linux/poll.c:87
#1  0x00007f7b36653f68 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007f7b36654429 in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007f7b3d2c8c06 in QEventDispatcherGlib::processEvents (this=0x1583770, flags=<optimized out>) at kernel/qeventdispatcher_glib.cpp:426
#4  0x00007f7b3d2983e2 in QEventLoop::processEvents (this=<optimized out>, flags=...) at kernel/qeventloop.cpp:149
#5  0x00007f7b3d298637 in QEventLoop::exec (this=0x7f7b1ed2dcd0, flags=...) at kernel/qeventloop.cpp:204
#6  0x00007f7b3d198067 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:501
#7  0x00007f7b3d27817f in QInotifyFileSystemWatcherEngine::run (this=0x1582f30) at io/qfilesystemwatcher_inotify.cpp:248
#8  0x00007f7b3d19b08b in QThreadPrivate::start (arg=0x1582f30) at thread/qthread_unix.cpp:298
#9  0x00007f7b3259f354 in ?? () from /usr/lib/libGL.so.1
#10 0x00007f7b371bdefc in start_thread (arg=0x7f7b1ed2e700) at pthread_create.c:304
#11 0x00007f7b4052759d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#12 0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7f7b40c3f7c0 (LWP 3004)):
[KCrash Handler]
#6  0x00007f7b3d5ef8e0 in QString::shared_null () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#7  0x00007f7b4083a756 in MDWSlider::update (this=0x1573160) at ../../kmix/gui/mdwslider.cpp:1001
#8  0x00007f7b4083600b in ViewDockAreaPopup::refreshVolumeLevels (this=<optimized out>) at ../../kmix/gui/viewdockareapopup.cpp:168
#9  0x00007f7b40833311 in ViewBase::qt_metacall (this=0x1571d50, _c=QMetaObject::InvokeMetaMethod, _id=<optimized out>, _a=0x7fff4a9456e0) at ./viewbase.moc:87
#10 0x00007f7b408359e0 in ViewDockAreaPopup::qt_metacall (this=0x1571d50, _c=QMetaObject::InvokeMetaMethod, _id=<optimized out>, _a=0x7fff4a9456e0) at ./viewdockareapopup.moc:73
#11 0x00007f7b3d2adbe9 in QMetaObject::activate (sender=0x150acf0, m=<optimized out>, local_signal_index=<optimized out>, argv=0x0) at kernel/qobject.cpp:3566
#12 0x00007f7b408520cc in Mixer::qt_metacall (this=0x150acf0, _c=QMetaObject::InvokeMetaMethod, _id=<optimized out>, _a=0x7fff4a945830) at ./mixer.moc:82
#13 0x00007f7b3d2adbe9 in QMetaObject::activate (sender=0x1500d40, m=<optimized out>, local_signal_index=<optimized out>, argv=0x0) at kernel/qobject.cpp:3566
#14 0x00007f7b4080f38c in Mixer_Backend::readSetFromHW (this=0x1500d40) at ../../kmix/backends/mixer_backend.cpp:155
#15 0x00007f7b4081f725 in sink_cb (c=<optimized out>, i=<optimized out>, eol=<optimized out>) at ../../kmix/backends/mixer_pulse.cpp:191
#16 0x00007f7b3ec27ce4 in ?? () from /usr/lib/x86_64-linux-gnu/libpulse.so.0
#17 0x00007f7b36b755f3 in ?? () from /usr/lib/x86_64-linux-gnu/libpulsecommon-1.0.so
#18 0x00007f7b36b75963 in pa_pdispatch_run () from /usr/lib/x86_64-linux-gnu/libpulsecommon-1.0.so
#19 0x00007f7b3ec1dc1d in ?? () from /usr/lib/x86_64-linux-gnu/libpulse.so.0
#20 0x00007f7b36b7a209 in ?? () from /usr/lib/x86_64-linux-gnu/libpulsecommon-1.0.so
#21 0x00007f7b3ea0bb23 in ?? () from /usr/lib/x86_64-linux-gnu/libpulse-mainloop-glib.so.0
#22 0x00007f7b36653a5d in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#23 0x00007f7b36654258 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#24 0x00007f7b36654429 in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#25 0x00007f7b3d2c8b9f in QEventDispatcherGlib::processEvents (this=0x1029ad0, flags=<optimized out>) at kernel/qeventdispatcher_glib.cpp:424
#26 0x00007f7b3dfaf21e in QGuiEventDispatcherGlib::processEvents (this=<optimized out>, flags=<optimized out>) at kernel/qguieventdispatcher_glib.cpp:204
#27 0x00007f7b3d2983e2 in QEventLoop::processEvents (this=<optimized out>, flags=...) at kernel/qeventloop.cpp:149
#28 0x00007f7b3d298637 in QEventLoop::exec (this=0x7fff4a946400, flags=...) at kernel/qeventloop.cpp:204
#29 0x00007f7b3d29d6c7 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1148
#30 0x00007f7b40826cc2 in kdemain (argc=3, argv=0x7fff4a946988) at ../../kmix/apps/main.cpp:76
#31 0x00007f7b4046530d in __libc_start_main (main=0x400630 <main(int, char**)>, argc=3, ubp_av=0x7fff4a946988, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fff4a946978) at libc-start.c:226
#32 0x0000000000400661 in _start ()

Reported using DrKonqi