It looks like it's because i have them set as sprites. when i made them a tile background it doesn't look lik they have the same issue.. But i need them as sprites so i can set their collision polygons..
and how do you mean window zoom? I use CTRL and Scroll to zoom - i'm assuming that is incorrect?
Yes do not use the regular window zoom controls. Go to the View tab at the top of C2 and you will see zoom controls.
Use those instead. I have had that same problem happen and can be very frustrating but your game is fine and is just happening because the zoom has a bug.