There is a trick which can solve your after battle CTDs, just wait some minutes -or until the music stop- before press the command to continue to campaign map. This solved all my CTDs!. It sounds like a joke but it worked for me, and a lot of guys i have read here. When the battles have more than 2000 units it is possible to have the error -at least for me-, so better be patient hehe. The other CTDs during battle sounds like overheating...

I only had one unsolved CTD in a siege where i got it in the middle of the battle. I have had other bigger and longer battles than this and no problems, so it seems like a random CTD.