I had some major stuttering, freezing, and lock-up problems, but I solved it now...
I have another problem that is bigger than the above ones.
I have some big AI problems with elevators. Yes, I said elevators.
Like, there is the part in the "Point Insertion" chapter, when you run like hell away from the masked guys and they get you. After the screen goes white, you suddenly meet Alyx. Well here is my problem: When Alyx is talking, she is going to the elevator and pushes the callbutton. When the elevator arrives and the door opens, Alyx suddenly cuts the talking and just stays there in front of the elevator doing nothing. I tried everything: pushing the button myself, try to push Alyx in the cabin, shooting Alyx

, even tried to noclip down the shaft but nothing happens. This is happening when I arrive at Black Mesa East, when the doc calls the elevator. She shuts up, and just stand there, no matter what I do. She refuses to enter the cabin. This stands for all the levator that need AI operating.
Is there a fix for this? Please help me!