Uh, one 'millisecond' is a thousandth of a second. 5000 is FIVE SECONDS. Do you really need it to wait five seconds between each move of the ship? Remember, this is not per square, this is per FRAME in animation. Assuming 30 frames per second that's forcing a second of animation to Last 150 seconds.
Somehow it's not surprising that setting such a high value would cause some sort of overflow or lockup. I've been using a value of 5, yes 5, for a long time now. I've got Win98 running on an AMD Duron.