problem with half-life 2

[theMan]

i decided to start playing hl2 again, and i really forgot how fun it was!! wow! anyways, i got to the black mesa east part, where that mossman lady is supposed to lead me to the scientist dude. she gets to an elevator, and calls it up, and then she just stops talking, and doesnt do anything. she just stands there, and i cant do anything. the AI is broken. i tried reloading the game, i tried opening a saved game right before i got to that chapter, but it was still broken. please help!