Version:           3.0 (using KDE 4.1.2)
OS:                Linux
Installed from:    Ubuntu Packages

What I did: 
I started KDE, did clicked on the upgrade notification and did the upgrade with the adept upgrade manager (not a dist-upgrade, just about 56 new packages, I had not upgraded for some week). 
I worked with Firefox, I think, during the upgrade. 

During the Upgrade kmix crashed; I could not see any reaseon for the crash. I got this error log form kcrask: 

Anwendung: KMix (kmix), Signal SIGABRT
(no debugging symbols found) # <--This message 30 times
[Thread debugging using libthread_db enabled]
[New Thread 0xb64848d0 (LWP 6104)]
(no debugging symbols found) # <--This message 50 times
[KCrash handler]
#6  0xb7fbc430 in __kernel_vsyscall ()
#7  0xb7e0c880 in raise () from /lib/tls/i686/cmov/libc.so.6
#8  0xb7e0e248 in abort () from /lib/tls/i686/cmov/libc.so.6
#9  0xb75c9795 in qt_message_output () from /usr/lib/libQtCore.so.4
#10 0xb75c9872 in qFatal () from /usr/lib/libQtCore.so.4
#11 0xb75c9915 in qt_assert () from /usr/lib/libQtCore.so.4
#12 0xb79d957a in ?? () from /usr/lib/libsolid.so.4
#13 0xb79d987f in ?? () from /usr/lib/libsolid.so.4
#14 0xb76d6a60 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#15 0xb76d77e2 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#16 0xb79eb883 in ?? () from /usr/lib/libsolid.so.4
#17 0xb7a1149e in ?? () from /usr/lib/libsolid.so.4
#18 0xb7a1158a in ?? () from /usr/lib/libsolid.so.4
#19 0xb752e26e in ?? () from /usr/lib/libQtDBus.so.4
#20 0xb7535627 in ?? () from /usr/lib/libQtDBus.so.4
#21 0xb76d1771 in QObject::event () from /usr/lib/libQtCore.so.4
#22 0xb6cff8ec in QApplicationPrivate::notify_helper ()
   from /usr/lib/libQtGui.so.4
#23 0xb6d0776e in QApplication::notify () from /usr/lib/libQtGui.so.4
#24 0xb7c4372d in KApplication::notify () from /usr/lib/libkdeui.so.5
#25 0xb76c1e61 in QCoreApplication::notifyInternal ()
   from /usr/lib/libQtCore.so.4
#26 0xb76c2ae5 in QCoreApplicationPrivate::sendPostedEvents ()
   from /usr/lib/libQtCore.so.4
#27 0xb76c2cdd in QCoreApplication::sendPostedEvents ()
   from /usr/lib/libQtCore.so.4
#28 0xb76ec82f in ?? () from /usr/lib/libQtCore.so.4
#29 0xb66a76f8 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#30 0xb66aada3 in ?? () from /usr/lib/libglib-2.0.so.0
#31 0xb66aaf61 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#32 0xb76ec478 in QEventDispatcherGlib::processEvents ()
   from /usr/lib/libQtCore.so.4
#33 0xb6d99ee5 in ?? () from /usr/lib/libQtGui.so.4
#34 0xb76c052a in QEventLoop::processEvents () from /usr/lib/libQtCore.so.4
#35 0xb76c06ea in QEventLoop::exec () from /usr/lib/libQtCore.so.4
#36 0xb76c2da5 in QCoreApplication::exec () from /usr/lib/libQtCore.so.4
#37 0xb6cff767 in QApplication::exec () from /usr/lib/libQtGui.so.4
#38 0xb7f51abb in kdemain () from /usr/lib/libkdeinit4_kmix.so
#39 0x080485a2 in _start ()
#0  0xb7fbc430 in __kernel_vsyscall ()