I installed VirtualBox 5.0.28 in Mac then installed Kubuntu 16.04
Once I installed the Guest Addition CD drivers and rebooted I notice the crash starts to happen from time to time especially when you move from one virtual desktop to another and move windows around. I set my resulation at 2K and have 2 monitors. 

My MAC: 10.10.5 (14F2009)
Monitors (2x): 27-inch (2560 x 1440)
MacBook Pro (Retina, 15-inch, Early 2013)
CPU: 2.4 GHz Intel Core i7
Memory: 16 GB 1600 MHz DDR3
Video Card: NVIDIA GeForce GT 650M 1024 MB

At my home computer using Windows 10 and VirtualBox 5 the same exact problem occurs. This time I have nVidia Titan GPU with one monitor and 4 virtual desktop in Kubuntu. Crashes are usually 10 times in one hour. I also tried Kubuntu 14.04 and also same problem. Something to do with VirtualBox and full screen.

Here is the crash dump:

Application: Plasma (plasmashell), signal: Segmentation fault
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[Current thread is 1 (Thread 0x7f5e45a9d8c0 (LWP 3850))]

Thread 12 (Thread 0x7f5d775f9700 (LWP 3879)):
#0  0x00007f5e401a6b5d in poll () at ../sysdeps/unix/syscall-template.S:84
#1  0x00007f5e3cf3c39c in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007f5e3cf3c4ac in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007f5e40ad37eb in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#4  0x00007f5e40a7ab4a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#5  0x00007f5e40897834 in QThread::exec() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#6  0x00007f5d79ad77d7 in KCupsConnection::run() () from /usr/lib/x86_64-linux-gnu/libkcupslib.so
#7  0x00007f5e4089c7be in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#8  0x00007f5e3f98970a in start_thread (arg=0x7f5d775f9700) at pthread_create.c:333
#9  0x00007f5e401b282d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 11 (Thread 0x7f5d8bb28700 (LWP 3878)):
#0  0x00007f5e401a6b5d in poll () at ../sysdeps/unix/syscall-template.S:84
#1  0x00007f5e3cf3c39c in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007f5e3cf3c4ac in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007f5e40ad37eb in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#4  0x00007f5e40a7ab4a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#5  0x00007f5e40897834 in QThread::exec() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#6  0x00007f5e43ac5ed6 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#7  0x00007f5e4089c7be in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#8  0x00007f5e3f98970a in start_thread (arg=0x7f5d8bb28700) at pthread_create.c:333
#9  0x00007f5e401b282d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 10 (Thread 0x7f5e12528700 (LWP 3877)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007f5e454e4bd4 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Script.so.5
#2  0x00007f5e454e4c19 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Script.so.5
#3  0x00007f5e3f98970a in start_thread (arg=0x7f5e12528700) at pthread_create.c:333
#4  0x00007f5e401b282d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 9 (Thread 0x7f5e13bb7700 (LWP 3876)):
#0  0x00007f5e4089b7a7 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#1  0x00007f5e40ad3031 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#2  0x00007f5e3cf3bdd1 in g_main_context_check () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007f5e3cf3c340 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007f5e3cf3c4ac in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#5  0x00007f5e40ad37eb in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#6  0x00007f5e40a7ab4a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#7  0x00007f5e40897834 in QThread::exec() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#8  0x00007f5e4313f3c5 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#9  0x00007f5e4089c7be in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#10 0x00007f5e3f98970a in start_thread (arg=0x7f5e13bb7700) at pthread_create.c:333
#11 0x00007f5e401b282d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 8 (Thread 0x7f5e19a0d700 (LWP 3875)):
#0  0x00007f5e401a269d in read () at ../sysdeps/unix/syscall-template.S:84
#1  0x00007f5e3cf7f740 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007f5e3cf3be84 in g_main_context_check () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007f5e3cf3c340 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007f5e3cf3c4ac in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#5  0x00007f5e40ad37eb in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#6  0x00007f5e40a7ab4a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#7  0x00007f5e40897834 in QThread::exec() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#8  0x00007f5e4313f3c5 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#9  0x00007f5e4089c7be in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#10 0x00007f5e3f98970a in start_thread (arg=0x7f5e19a0d700) at pthread_create.c:333
#11 0x00007f5e401b282d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 7 (Thread 0x7f5e1e240700 (LWP 3874)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007f5e23957aa3 in ?? () from /usr/lib/x86_64-linux-gnu/dri/swrast_dri.so
#2  0x00007f5e23957907 in ?? () from /usr/lib/x86_64-linux-gnu/dri/swrast_dri.so
#3  0x00007f5e3f98970a in start_thread (arg=0x7f5e1e240700) at pthread_create.c:333
#4  0x00007f5e401b282d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 6 (Thread 0x7f5e1ea41700 (LWP 3873)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007f5e23957aa3 in ?? () from /usr/lib/x86_64-linux-gnu/dri/swrast_dri.so
#2  0x00007f5e23957907 in ?? () from /usr/lib/x86_64-linux-gnu/dri/swrast_dri.so
#3  0x00007f5e3f98970a in start_thread (arg=0x7f5e1ea41700) at pthread_create.c:333
#4  0x00007f5e401b282d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 5 (Thread 0x7f5e1f242700 (LWP 3872)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007f5e23957aa3 in ?? () from /usr/lib/x86_64-linux-gnu/dri/swrast_dri.so
#2  0x00007f5e23957907 in ?? () from /usr/lib/x86_64-linux-gnu/dri/swrast_dri.so
#3  0x00007f5e3f98970a in start_thread (arg=0x7f5e1f242700) at pthread_create.c:333
#4  0x00007f5e401b282d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 4 (Thread 0x7f5e1fa43700 (LWP 3871)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007f5e23957aa3 in ?? () from /usr/lib/x86_64-linux-gnu/dri/swrast_dri.so
#2  0x00007f5e23957907 in ?? () from /usr/lib/x86_64-linux-gnu/dri/swrast_dri.so
#3  0x00007f5e3f98970a in start_thread (arg=0x7f5e1fa43700) at pthread_create.c:333
#4  0x00007f5e401b282d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 3 (Thread 0x7f5e2a406700 (LWP 3866)):
#0  0x00007f5e3cf7f710 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#1  0x00007f5e3cf3be84 in g_main_context_check () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007f5e3cf3c340 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007f5e3cf3c4ac in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007f5e40ad37eb in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#5  0x00007f5e40a7ab4a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#6  0x00007f5e40897834 in QThread::exec() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#7  0x00007f5e4313f3c5 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#8  0x00007f5e4089c7be in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#9  0x00007f5e3f98970a in start_thread (arg=0x7f5e2a406700) at pthread_create.c:333
#10 0x00007f5e401b282d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 2 (Thread 0x7f5e30de2700 (LWP 3863)):
#0  0x00007f5e401a6b5d in poll () at ../sysdeps/unix/syscall-template.S:84
#1  0x00007f5e4426bc62 in ?? () from /usr/lib/x86_64-linux-gnu/libxcb.so.1
#2  0x00007f5e4426d8d7 in xcb_wait_for_event () from /usr/lib/x86_64-linux-gnu/libxcb.so.1
#3  0x00007f5e32f30629 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5
#4  0x00007f5e4089c7be in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#5  0x00007f5e3f98970a in start_thread (arg=0x7f5e30de2700) at pthread_create.c:333
#6  0x00007f5e401b282d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 1 (Thread 0x7f5e45a9d8c0 (LWP 3850)):
[KCrash Handler]
#6  __memmove_ssse3_back () at ../sysdeps/x86_64/multiarch/memcpy-ssse3-back.S:1574
#7  0x00007f5e235e74ad in ?? () from /usr/lib/x86_64-linux-gnu/dri/swrast_dri.so
#8  0x00007f5e235e5d95 in ?? () from /usr/lib/x86_64-linux-gnu/dri/swrast_dri.so
#9  0x00007f5e291eac1f in ?? () from /usr/lib/x86_64-linux-gnu/qt5/qml/org/kde/plasma/core/libcorebindingsplugin.so
#10 0x00007f5e291ebe44 in ?? () from /usr/lib/x86_64-linux-gnu/qt5/qml/org/kde/plasma/core/libcorebindingsplugin.so
#11 0x00007f5e291ec803 in ?? () from /usr/lib/x86_64-linux-gnu/qt5/qml/org/kde/plasma/core/libcorebindingsplugin.so
#12 0x00007f5e291ecd24 in ?? () from /usr/lib/x86_64-linux-gnu/qt5/qml/org/kde/plasma/core/libcorebindingsplugin.so
#13 0x00007f5e43b642d8 in QQuickWindowPrivate::updateDirtyNode(QQuickItem*) () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#14 0x00007f5e43b64b4b in QQuickWindowPrivate::updateDirtyNodes() () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#15 0x00007f5e43b64cc0 in QQuickWindowPrivate::syncSceneGraph() () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#16 0x00007f5e43b3312c in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#17 0x00007f5e43b342a1 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#18 0x00007f5e4158005c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#19 0x00007f5e41585516 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#20 0x00007f5e40a7d38b in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#21 0x00007f5e40ad25ed in QTimerInfoList::activateTimers() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#22 0x00007f5e40ad2af1 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#23 0x00007f5e3cf3c1a7 in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#24 0x00007f5e3cf3c400 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#25 0x00007f5e3cf3c4ac in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#26 0x00007f5e40ad37cf in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#27 0x00007f5e40a7ab4a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#28 0x00007f5e40a82bec in QCoreApplication::exec() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#29 0x0000000000432d4a in main ()