it happens to me as well. but only happens (not always) if you try to put the item into cube by dragging the item over cube. It doesnot happen when you open cube and place the item into cube over a open slot.
not sure but it happens when you try to put the item into cube (by dragging) on to the edge of cube.
other than that, sorry i dont know. game crashes many times on my computer. i learned to live with that