So i played the same battle that it gave me the CTD all the time in Medium settings with Shader Model 3(low)-AA:0,AF:Bilinear and only SSAO shadow checked and it CTD again with these settings to.But i think i found something.I play again and again with different settings the same battle and i noticed that the CTD occures when i change the Behaviour of some of the units with the special ability they have the "Light Infantry Behaviour".Dragoons and some of the infantry and it happens after some seconds i use the special ability.So i played again with the medium settings and i did not use the special ability and it work...!!I finish the battle with a victory of course
and all went good no CTD.I change the settings with my usual Ultra and stuff and i finish again the battle and no CTD again.I don't know if its the reason for all of the CTD for the Campaign battles but it work for me.And i don't think it was a coincidence.So u guys give it a try.Who knows.Cheers.