On the game+mod crashing problem ...
Do you play any other intense graphic games on the 3 PC's you mentioned? If you do, have you had any crashes?
The reason I mention it is that the Nvidia GeForce 8400M GS driver has had problems with overheating, see ...
Also, make sure you have the latest drivers for your card.
For your information you are the first person to report a problem (crash) with the Diplomacy mod (with >500 downloads).
The most common problems with the Maelstrom mod are those related to Graphics Cards (and their Drivers) and also the 32bit RAM limitations of Sins (i.e going over 2GB).
First of all I have never had any issues with the 8400m gs plays sins great!
"Do you play any other intense graphic games on the 3 PC's you mentioned? If you do, have you had any crashes?"
Yes like crysis, farcry2, dragon age, just case 2...etc never had problems on any of my PCs but the only game that I am having problem beside this mod is Elemental war of magic but they are working on that!