Photoshop white grid lines - huge problem with (probably) easy solution

I'm working on a game with lots of precise pixel artwork, and I need to be zoomed in on my work 24/7. Recently I switched to a Mac computer and this version of Photoshop automatically creates an atomically thick grid when you zoom in too close. This is a huge problem. I've looked in the Preferences but I just can't find anything that will turn it off. I remember being able to do this before, but I don't actually remember how. It might not look like a huge problem, but believe me when I say that it is. Please help me!