This has happened twice, so I thought it could be a bug.
I get CTD while sieging Makkada in the human quest. It always happens after passing the second wall, and trying to attack the third. This time I was sellecting the archers when it happened. It wasn't related with the chat, as it was closed and there was no one talking. I didn't have any kind of lag or slowdown before the CTD, it happens suddendly. "DoF.exe doesn't respond", that's the error I get.
It hasn't happened on any other circumstances that I recall. Only when you press 3 keys at the same time writting in the chat, but it's not related to that.
Edit: Not sure if it goes on the CTD topic, as it only happens in the quest.