Well week 3 with Vista, and no luck getting it to allow the usage of my Boat, When I run the game, even with MODS disabled, CRASH DIVE on vista, I guess I better uninstall the Japanese Prototype Operating SW and go back to XP....any ideas? It gets to the Find em Catch em sink em and then CRASHES..
I wouldn't totally blame the problem on Vista. I used SP1 Vista for two years (Dec '08-Dec '10) before I upgraded to Windows 7 (because of a hard-drive failure) and I never experienced any issues with SH4.
These are just going to be my un-professional suggestions, but before defaulting back to XP I would perhaps try a fresh re-install of SH4 if you haven't done so already. Also, make sure you are running the game "As Administrator" and also check and make sure that your desktop launch icon (assuming you use one) has a target ending in "sh4.exe".
If I recall correctly, the above said things to be a fairly common cause for game errors. I would check those first before going through the hassle of switching to XP.
You wouldn't by chance be using Mk10 torpedoes would you? That has been my one issue with this game, I can never get Mk10's to work, they always result in a CTD. I've tried it with and without mods on both Vista and Windows 7 with no luck. If I equip Mk10's and then try to head out to sea (aka "start mission") I always get a CTD. I've tried with different boats, different torp loadouts etc, but even if I equip one Mk10 I will get a CTD. Guaranteed.
Figured I'd mention that too because, in my experience, if you are trying to load Mk10's they will result in a problem similar to yours.
Do you have Vista 32 or 64 bit? I've been running Vista 64 for a couple of years now and haven't had one problem. No problems running SHIV, mods or any other game/program. I wouldn't necessarily blame the operating system. Did you disable UAC before installing SHIV? Also, are you signed-in to Vista as "Administrator"?
Make sure you update absolutely everything. Get all Vista service packs and the most up to date drivers you can find. The Operating system was notoriously buggy on release and remained so for some time afterwards.
Once you've done that ensure your Silent Hunter 4 is not installed to program files and that the shortcut is pointed at "Sh4.exe" not "Gu.exe"
Also, could you post a list of computer specifications? Vista chews a lot more resources than XP and it's possible your computer can't keep up with the additional usage.