Strange Jerky Pixelation

[nickbrok]

Hey all. Since Christmas, Photoshop (which I use daily for my job) has stopped zooming cleanly. There is a strange pixelation that occurs. Also, There is a skip/delay of one action on everything I do, which is infuriating and tripping up my work-flow. Here is a screenshot of what it look like.

Any thoughts or guidance?

Cheers all.

Nick