Having issues with Photoshop Elements giving random multi-colour grid lines anytime a drawing is open. It doesn't occur with pictures, but does happen with any PDF files or drawings. I have already tried reinstalling, rebuilding the full computer, changing RAM and also another PC which also gets the same issue. GPU drivers are all up to date also on this Windows 7 machine.
The screenshot below is the issue itself. the black lines change colour when you move the drawing around, with some lines disappearing and re-appearing again randomly.
Anyone got any ideas as to the issue?