I've just had two crashes shortly after the initial cutscene+dialogue for chapter 6. In both crashes I had just finished chapter 5, got out of the underdark, and had dialogue initiated by the elves on the surface. They took me to elharn (i think thats his name?), and i finished the conversation both times with a spell being cast on viconia (an oath to swear her loyalty or something). The crash occurred VERY shortly after dialogue had finished (ie 10 seconds) in both cases.
1st Crash: I finished the dialogue sequence without saving, so the save file is the closest auto-save (which is common to both crashes). I then went to the inventory screen and crashed (although i'm not sure which character caused the crash...i think it might have occurred just after i removed adamantite dust from korgan/dorn/imoen??)
2nd Crash: I was able to quicksave immediately after dialogue finished. I then went to the inventory screen, and the crash occurred right as i was clicking on viconia's portrait... i can't remember if i did this the 1st time or not. It may have been imoen's portrait the 1st time)