After buying a Marque I had a few components at the bottom of the 'modify' list. I deleted these by choosing one using the mouse, then clicking 'end production' with the mouse. I then used the enter button to accept. This moves the red selected part down one notch to the next component on the list. I use the mouse to hit 'end production', and hit enter to accept. (it's just faster this way to delete a lot of items).

When it get to the bottom of the list, the very last item is not visible. it lies below the window, but is selected. When this item is deleted, it crashes the game.