I came across your query too late to answer it as you have solved it, but you would be surprised how many people fail to add the 3.1 submod, I have given this solution several times across this forum as well as my Let's Plays, I would also suggest you apply a 4gb file to your exe's as it helps stabilize the mod as it has a high content, RTW only has 2gb memory and this file allows up to 4gb, I use it in every mod and rarely ever have ctd's, I can't add any more info about it as I would contravene TWC rules so just google it