SH3 questions are better asked here:
http://www.subsim.com/radioroom/forumdisplay.php?f=182
The forum part that we are in now is for the latest (upcomming) release of Silent Hunter Online.
That said, what sort of hardware do you have? In particular the Graphics chipset/card. Is it a dedicated graphics card, or is it onboard the Motherboard? The latter option usually has insufficient capacity to handle the 3d aspects of games like SH3.
So, please post some more specs.