Hi Paul, how large of an array are you trying to make?

Is it possible for you to send me the 3DM file as well so I can try to repeat the problem over here?

While you are in the middle of moving your mouse around and adjusting options in the array tools, MoI only draws a lightweight proxy object on the screen to give faster feedback. It's only when you are completing the array that the full object copies are being made. So if you are overloading things by making a large number of copies of a fairly complex object, then that's the point where you will run into problems with consuming all available memory.

- Michael