Strange; I wonder what your system is doing that would cause that. I've been able to successfully ScrPrt and tab-out of SH3 and SH4 under XP pro and now Vista64 Pro.
But anyway...
MoBo is not really designed to be a DRT for the entire ocean(s) or at least not version 1.1. You would need to track your position by marking it with the pencil on the nav map in the game.
For your situation, MoBo could be used as a maneuvering board station for solving relative motion problems and tracking/intercepting contacts within sensor range or via radio contact data.
As a moboard station, your subs position is always at the center... there's no guesswork involved. You're tracking the relative motion of the target to determine true course and speed. Once you have that information, you can plot your attack strategy.
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