on the moon in archer line in one of the small buildings outside the bigger building that is in the area to the left of where you first start patrol just before the path leading to the hell mouth there is a chest that occasionally spawns inside that NEVER OPENS! it doesnt even show the open button, it just sits there not working. its the only one i have encountered in the game but ive seen this same chest do it probably 3 times already now and have never gotten it to open.