Random black sections

[dwatja]

We have observed that periodically the screens partially fill with black graphical artifacts such as in the picture below. The graphical artifacts may sometimes be cleared by tapping on the screen (force it to redraw?) or by unplugging/replugging the display. This issue is not easily reproducible.
The Red arrows point to the black portions of the screen. They are not normally black.

direct link to image (https://www.dropbox.com/s/pvuls6g4yw...ge003.jpg?dl=0)