It has nothing to do with a trigger or the vent. As soon as I try to access the hallway or the adjacent room (the one with the red button), the game crashes. It does not matter from which direction I enter. Both areas have a view to the "bay area", but are separated by a door.
My guess is that something from the "bay area" is the source of the problem. Like a light or something, I don't know.
Is there maybe something only viewable while you are in those areas? Because I can see the "bay area" with the ship and the trucks from the vent just fine. No crash there.
As far as I know Portal for Mac uses OpenGL. Can you switch in Windows also to OpenGL and see if you have the same problem?
I would understand if you don't want to adress this issue any further since a fix means probably a lot of work for you.
I will attach one of the crash logs in case somebody can use thishl2_osx_2010-05-18-184447_Viking.crash.txt.
By the way, I enjoyed your map pack a lot and was able to finish all of it!
A big thanks to the guys developing this!!!