A strange gray grid on my workspace

[Calico]

Hello !

I was working on an image and my cursor was dragged off the workspace. After that, a gray area with crisscrossed lines appeared on the outside of my image, covering my entire workspace except for the image itelf.
I have gone into preferences and tried putting it back to the default workspace but that didn't help. I have tried all the grid and guide options and nothing has worked.
It also won't allow me to minimize the image, just close it.
Anybody else have this problem and does anyone know how to fix it ?

I have attached a screenshot.

TIA !