i formely had a 32 bits system and i managed to get the ctds under control,but since i switched to 64 bits it CTd all the time.by fiddling around i managed to get it almost ctd free(ieven have 2 different battle with each 2 ennemy quaddi stack that i beaten then i could occupy the city without any problem...to me it was unheard of)
but how you ask me...first use cff explorer and allow the exe you use to acces more than 2gb of ram(in my case alx.exe)
secondly:you start the game normaly and once the screen with single player,load,custom battle etc appear then ctr alt del,then go to process,then select the exe with rigth click and click on set priority set it to LOW.
then set affinity,untick all cores but the last one.
the thing with the cff explorer is permanent,the other 2 steps you have to do it every single time you start the game,but thankfully it take only 15 second.i have windows 7 and since i use this i can squash quaddis and incompetent valens troops at will even while beseiging without any ctds,enjoy it really work for me....the only downside is that the game will take approx 15 second to load back after a battle,but hey to save the ctd!