Application: plasma-desktop (4.11.11)
KDE Platform Version: 4.13.3
Qt Version: 4.8.6
Operating System: Linux 3.19.0-80-generic x86_64
Distribution: Ubuntu 14.04.5 LTS

-- Information about the crash:
Plasma crashed when i clicked on miniature in taskbar (KDE taskbar or SmoothTasks) of any app. These worked well until two days ago. 
My system is updated. I type in terminal "plasma-desktop" and Plasma works again.
My last updates:
~$ more /var/log/apt/history.log

I INSTALLED LECTOR DE PANTALLA GNOME-ORCA
Start-Date: 2018-02-02  19:57:23
Commandline: /usr/sbin/synaptic
Install: python3-pyatspi:amd64 (2.10.0+dfsg-1, automatic), gir1.2-wnck
-3.0:amd64 (3.4.7-0ubuntu3.1, automatic), gnome-orca:amd64 (3.10.3-0ub
untu1), python3-brlapi:amd64 (5.0-2ubuntu2, automatic), libwnck-3-0:am
d64 (3.4.7-0ubuntu3.1, automatic), libxres1:amd64 (1.0.7-1, automatic)
, liblouis-data:amd64 (2.5.3-2ubuntu1.2, automatic), libwnck-3-common:
amd64 (3.4.7-0ubuntu3.1, automatic), liblouis2:amd64 (2.5.3-2ubuntu1.2
, automatic), python3-speechd:amd64 (0.8-5ubuntu1, automatic), python3
-louis:amd64 (2.5.3-2ubuntu1.2, automatic), python3-xdg:amd64 (0.25-4,
 automatic), libatk-adaptor:amd64 (2.10.2-2ubuntu1, automatic), libgai
l-common:amd64 (2.24.23-0ubuntu1.4, automatic)
End-Date: 2018-02-02  19:57:54

I PURGED LECTOR DE PANTALLA GNOME-ORCA
Start-Date: 2018-02-02  20:52:12
Commandline: /usr/sbin/synaptic
Purge: gnome-orca:amd64 (3.10.3-0ubuntu1)
End-Date: 2018-02-02  20:52:39

Start-Date: 2018-02-02  23:00:48
Commandline: apt-get autoremove
Remove: python3-pyatspi:amd64 (2.10.0+dfsg-1), gir1.2-wnck-3.0:amd64 (
3.4.7-0ubuntu3.1), python3-brlapi:amd64 (5.0-2ubuntu2), libwnck-3-0:am
d64 (3.4.7-0ubuntu3.1), libxres1:amd64 (1.0.7-1), liblouis-data:amd64 
(2.5.3-2ubuntu1.2), libwnck-3-common:amd64 (3.4.7-0ubuntu3.1), libloui
s2:amd64 (2.5.3-2ubuntu1.2), python3-speechd:amd64 (0.8-5ubuntu1), pyt
hon3-louis:amd64 (2.5.3-2ubuntu1.2), python3-xdg:amd64 (0.25-4), libat
k-adaptor:amd64 (2.10.2-2ubuntu1), libgail-common:amd64 (2.24.23-0ubun
tu1.4)
End-Date: 2018-02-02  23:01:12

Start-Date: 2018-02-02  23:02:11
Commandline: apt-get upgrade
Upgrade: chromium-codecs-ffmpeg-extra:amd64 (63.0.3239.132-0ubuntu0.14
.04.1, 64.0.3282.119-0ubuntu0.14.04.1), libcurl3:amd64 (7.35.0-1ubuntu
2.13, 7.35.0-1ubuntu2.14), libcurl4-openssl-dev:amd64 (7.35.0-1ubuntu2
.13, 7.35.0-1ubuntu2.14), libcurl3-gnutls:amd64 (7.35.0-1ubuntu2.13, 7
.35.0-1ubuntu2.14)
End-Date: 2018-02-02  23:02:18

The crash can be reproduced every time.

-- Backtrace:
Application: Shell de escritorio Plasma (plasma-desktop), signal: Segmentation fault
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[Current thread is 1 (Thread 0x7f2f8b08c7c0 (LWP 4548))]

Thread 4 (Thread 0x7f2f5d6f2700 (LWP 4549)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007f2f83d34ffb in ?? () from /usr/lib/x86_64-linux-gnu/libQtScript.so.4
#2  0x00007f2f83d35039 in ?? () from /usr/lib/x86_64-linux-gnu/libQtScript.so.4
#3  0x00007f2f7e5e0184 in start_thread (arg=0x7f2f5d6f2700) at pthread_create.c:312
#4  0x00007f2f8a98103d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111

Thread 3 (Thread 0x7f2edbcb8700 (LWP 4550)):
#0  0x00007f2f7e5e37de in __pthread_mutex_unlock_usercnt (decr=1, mutex=0x7f2ed4000a60) at pthread_mutex_unlock.c:57
#1  __GI___pthread_mutex_unlock (mutex=0x7f2ed4000a60) at pthread_mutex_unlock.c:310
#2  0x00007f2f7df109b1 in g_mutex_unlock () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007f2f7dece0f0 in g_main_context_acquire () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007f2f7deceea5 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#5  0x00007f2f7decf0ec in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#6  0x00007f2f8754a7be in QEventDispatcherGlib::processEvents (this=0x7f2ed40008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:436
#7  0x00007f2f8751c0af in QEventLoop::processEvents (this=this@entry=0x7f2edbcb7de0, flags=...) at kernel/qeventloop.cpp:149
#8  0x00007f2f8751c3a5 in QEventLoop::exec (this=this@entry=0x7f2edbcb7de0, flags=...) at kernel/qeventloop.cpp:204
#9  0x00007f2f87418c5f in QThread::exec (this=this@entry=0x1fa85d0) at thread/qthread.cpp:537
#10 0x00007f2f874fd823 in QInotifyFileSystemWatcherEngine::run (this=0x1fa85d0) at io/qfilesystemwatcher_inotify.cpp:265
#11 0x00007f2f8741b32f in QThreadPrivate::start (arg=0x1fa85d0) at thread/qthread_unix.cpp:349
#12 0x00007f2f7e5e0184 in start_thread (arg=0x7f2edbcb8700) at pthread_create.c:312
#13 0x00007f2f8a98103d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111

Thread 2 (Thread 0x7f2ecbfff700 (LWP 4554)):
#0  0x00007f2f8a973c9d in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007f2f7decefe4 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007f2f7decf0ec in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007f2f8754a7be in QEventDispatcherGlib::processEvents (this=0x7f2ec40008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:436
#4  0x00007f2f8751c0af in QEventLoop::processEvents (this=this@entry=0x7f2ecbffede0, flags=...) at kernel/qeventloop.cpp:149
#5  0x00007f2f8751c3a5 in QEventLoop::exec (this=this@entry=0x7f2ecbffede0, flags=...) at kernel/qeventloop.cpp:204
#6  0x00007f2f87418c5f in QThread::exec (this=this@entry=0x25076a0) at thread/qthread.cpp:537
#7  0x00007f2f874fd823 in QInotifyFileSystemWatcherEngine::run (this=0x25076a0) at io/qfilesystemwatcher_inotify.cpp:265
#8  0x00007f2f8741b32f in QThreadPrivate::start (arg=0x25076a0) at thread/qthread_unix.cpp:349
#9  0x00007f2f7e5e0184 in start_thread (arg=0x7f2ecbfff700) at pthread_create.c:312
#10 0x00007f2f8a98103d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111

Thread 1 (Thread 0x7f2f8b08c7c0 (LWP 4548)):
[KCrash Handler]
#6  data (this=0x0) at /usr/include/qt4/QtCore/qsharedpointer_impl.h:587
#7  TaskManager::TaskItem::task (this=0x7f2f87883920 <QString::shared_null>) at ../../../libs/taskmanager/taskitem.cpp:135
#8  0x00007f2f5eb785e7 in ?? () from /usr/lib/kde4/plasma_applet_smooth-tasks.so
#9  0x00007f2f5eb786dd in ?? () from /usr/lib/kde4/plasma_applet_smooth-tasks.so
#10 0x00007f2f8690651a in QWidget::event (this=0x3e57720, event=0x7ffdd20cd670) at kernel/qwidget.cpp:8376
#11 0x00007f2f868b6e2c in QApplicationPrivate::notify_helper (this=this@entry=0x1973e30, receiver=receiver@entry=0x3e57720, e=e@entry=0x7ffdd20cd670) at kernel/qapplication.cpp:4567
#12 0x00007f2f868bd5dd in QApplication::notify (this=this@entry=0x1972a60, receiver=receiver@entry=0x3e57720, e=e@entry=0x7ffdd20cd670) at kernel/qapplication.cpp:4110
#13 0x00007f2f881e163a in KApplication::notify (this=0x1972a60, receiver=0x3e57720, event=0x7ffdd20cd670) at ../../kdeui/kernel/kapplication.cpp:311
#14 0x00007f2f8751d4dd in QCoreApplication::notifyInternal (this=0x1972a60, receiver=receiver@entry=0x3e57720, event=event@entry=0x7ffdd20cd670) at kernel/qcoreapplication.cpp:953
#15 0x00007f2f868bcd93 in sendEvent (event=<optimized out>, receiver=<optimized out>) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:231
#16 QApplicationPrivate::sendMouseEvent (receiver=receiver@entry=0x3e57720, event=event@entry=0x7ffdd20cd670, alienWidget=alienWidget@entry=0x3e57720, nativeWidget=nativeWidget@entry=0x1f447b0, buttonDown=buttonDown@entry=0x7f2f8739c318 <qt_button_down>, lastMouseReceiver=..., spontaneous=spontaneous@entry=true) at kernel/qapplication.cpp:3178
#17 0x00007f2f869319eb in QETWidget::translateMouseEvent (this=this@entry=0x1f447b0, event=event@entry=0x7ffdd20cd9f0) at kernel/qapplication_x11.cpp:4634
#18 0x00007f2f86931289 in QApplication::x11ProcessEvent (this=0x1972a60, event=event@entry=0x7ffdd20cd9f0) at kernel/qapplication_x11.cpp:3627
#19 0x00007f2f86958b32 in x11EventSourceDispatch (s=0x19755a0, callback=0x0, user_data=0x0) at kernel/qguieventdispatcher_glib.cpp:146
#20 0x00007f2f7decee04 in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#21 0x00007f2f7decf048 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#22 0x00007f2f7decf0ec in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#23 0x00007f2f8754a7be in QEventDispatcherGlib::processEvents (this=0x18ccaf0, flags=...) at kernel/qeventdispatcher_glib.cpp:436
#24 0x00007f2f86958be6 in QGuiEventDispatcherGlib::processEvents (this=<optimized out>, flags=...) at kernel/qguieventdispatcher_glib.cpp:204
#25 0x00007f2f8751c0af in QEventLoop::processEvents (this=this@entry=0x7ffdd20cddc0, flags=...) at kernel/qeventloop.cpp:149
#26 0x00007f2f8751c3a5 in QEventLoop::exec (this=this@entry=0x7ffdd20cddc0, flags=...) at kernel/qeventloop.cpp:204
#27 0x00007f2f87521b79 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1225
#28 0x00007f2f868b537c in QApplication::exec () at kernel/qapplication.cpp:3828
#29 0x00007f2f8ac8867c in kdemain (argc=1, argv=0x7ffdd20ce018) at ../../../../plasma/desktop/shell/main.cpp:126
#30 0x00007f2f8a8a4f45 in __libc_start_main (main=0x4006e0 <main(int, char**)>, argc=1, argv=0x7ffdd20ce018, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7ffdd20ce008) at libc-start.c:287
#31 0x000000000040070e in _start ()