I have an unusual CTD when I try to progress in this quest.

I'm playing on a German Oblivion. It is patched to 1.20... It has Shivering Isles (also a German version). I have installed the latest Unofficial Oblivion Patch and I have almost no other mods left.

I tried to do this quest the normal way, I talked to Cirroc who sends me out to the east side of bruma, I leave bruma, I start to go towards the questmarker but immediately when the NPC's are "spawned" (loaded by the PC) I get a CTD.

I tried to use an earlier save (where I did not have the quest) and go there, no problem, I tried to disable every mod (except shivering Isles) and go there still got a CTD. I tried movetoqt and got a CTD.

it seems to me that the NPC's have a "bad" script and that's causing my CTD but I have no idea how to fix this, except by progressing the quest with console commands.