Disappearing japanese ships, conveys, etc.

[I'm goin' down]

I have a problem. Many times I have observed and tried to engage a ship, convoy or task force that appears on the map. I change my course, drool all over myself, but by the time Imy bath tub arrives at the intersection on the map the enemy has simply disappeared, and the red rectangle on the map representing their location has faded away. I am sailing all over the Pacific chasing these damn phantoms. Is there a pixie in the computer? Like the couple said when the fire department pulled a boa constrictor from ther bathroom piping under their tiolet, "I just knew there was a snake sticking his head out, I just knew it." (They took him away to Happy Dale Sanitarium anyway!)