When I make a square or rectangular selection in Photoshop, and when I move it around, its edges disappear randomly when moving the selection. It seems that if I move it vertically, the top and bottom edge disappears, and when I move it horizontally, the left and right edge disappears. Only until I stop moving the selection around I can see all sides again.
If I move it fast enough, ALL edges disappear, and all reappear when I stop moving the selection. This all happens when I'm moving just the selection around, and am not moving any pixels of an image.