A friend has just shown me his Android tablet (Mediatek TT906), which runs perfectly except in one respect.

Whenever Play Store is selected, the square frames showing the various apps are blank and grey.  If one swipes upward, 
the app's drawing or picture is slowly revealed ... there is a distinctive line about 1/4 from the top of the screen
where the colour pictures start to be revealed and then moves up like a blind when continue swiping up. The next line of apps
is also grey boxes until the line is reached.

Weirdly, all the icons/frames/coloured pictures display fully and correctly when tablet is rotated to portrait.

Owner thinks that Play Store displayed correctly originally but this 'no graphics in landscape' started shortly after a few
times later.

It is only Play Store where this oddity happens, all other apps and pics/videos etc display full screen in any orientation.

Anyone got some thoughts on this please?