am walking through anvil castle and rubble falls from the celing, on going through to the dining room, a quest named "before the dawn" is triggered and the game CTDs, any idea which mod is doing this?

Rubble from the ceiling????

Post your load list.

Are you using OBSE? If so, get refscope, or FormID Finder, either will tell you which mod is dropping rubble on you.

ok, used refscope and it revealed TLC2.esp is the mod that drops the rubble