[Dogfish40]

Win? 7 ?
Well, as far as your system memory overall, I don't think there's any problem. They recommend a GeForce 8800 or better with some laptop versions not supported BUT...I use my Asus laptop with no problem at all.
SO, I suggest, One; try loading the game directly to the C/drive. IE;
C/Ubisoft/Silent Hunter5 Instead of C/Program Files/Ubisoft/Silen...
I don't know if this is the same with 5 as it was with 3&4 but this worked for them.
Two, Update your graphics drivers, check Directx version, and make sure your system is not interfering with the DRM, try shutting off your firewall temporarily. I'm trying to find something else I shut down, but that was for SH4 or 3 on my laptop.
If your CTD is immediate it might be the DRM. Try a few of these and keep posting. You'll get this running as long as your Copy is good.