Dragon Age Inquistion: Cannot view the bottom of ability trees

Hi, I am now up to level 15 in Dragon Age Inquisition after playing it a while and everything in the game appears to work fine except I cannot physically see the bottom of the ability trees when I view the tree to select new spells and passive abilities. My mouse when I wonder it down hoping it might still show me whats down there, doesn't. It just disappears. I can access the top half or the abilites shown near the upper half of the trees but I cannot even view the lower ones of some of the trees. I was wondering if anyone else has had this problem and how to fix it please?   

PC Version of Dragon Age Inquisition by the way.