Stuck in the chapter "Lambda Core" in Half - Life (minor spoilers)

I was playing HL and came to the lambda core chapter. After I finished the teleport puzzle, i came to a glass door with a scientist and security guard behind them. They draw weapons, then holster them, as they realize I'm Gordon. They are supposed to open the door, but they dont for me. It is them who give you the long jump boots. I couldn't find a solution for this except for the sudgestion to shoot the guard with the tau cannon to make them aggresive and chase after me so they can open the door. This does not happen however as the guard just stands there, and if you shoot the scientist then the game ends and puts me back to my last save. I need help...