IDE not displaying properly

My IDE The line that contains "File" "Edit" "Sketch" etc does not display at a readable size and all dropdown menus do the same thing .

I have experimented in the preferences file and can alter the sketch font size and type but nothing seems to alter the menu size.

I have experimented with JRE 1.6 and 1.8 without change

Can anyone suggest what might be causing this . It was right when I first downloaded the IDE which is the latest 1.5.8