This is not the normal "black screen"issue and I was shocked to eventually find out why. The normal advice of reconfiguring Xorg didn't work. Even booting into "Recovery Mode" did not help.
Here is the short end of the stick that fixed it:
sudo apt-get install mdm mate-desktop-environment
Yes you got it right, mdm and the mate-desktop-environment / gnome were somehow uninstalled. This must be whe........
This happens if you are running a kdenlive script from the shell of a remote machine without using SSH "-X" forwarding and it will also cause any areas where you write text to be a white screen for that duration.
melt FusionFestival.kdenlive
No LADSPA plugins were found!
Check your LADSPA_PATH environment variable.
[producer_xml] failed to load transition "qtblend"
[producer_xml] failed to load transition &q........
#if you have nvidia make sure you install the nvidia-cuda-toolkit so hardware acceleration can be used
wget http://ffmpeg.org/releases/ffmpeg-3.3.2.tar.bz2
tar -jxvf ffmpeg-3.3.2.tar.bz2
cd ffmpeg-3.3.2/
./configure --disable-yasm
install prefix /usr/local
source path ........
Jun 1 15:45:42 videoeditor-desktop org.mate.panel.applet.MintMenuAppletFactory[1882]: project_data:INFO Missing folder chosen by user:
Jun 1 15:45:42 videoeditor-desktop org.mate.panel.applet.MintMenuAppletFactory[1882]: project_data:INFO Removed missing file: MAH02949.MP4
Jun 1 15:45:57 videoeditor-desktop org.mate.panel.applet.MintMenuAppletFactory[1882]: ui_util:WARNING Icon theme media-playback-start not found. Will use backup........
To disable NCQ in the Linux kernel (change sda to match your device).
echo 1 > /sys/block/sda/device/queue_depth
To enable NCQ (change sda to match your device).
echo 31 > /sys/block/sda/device/queue_depth........