When Dr. Hawkins is telling you how to fire your weapon, move, etc. get to the point where he says he placed a gernade somewhere around there. Then go pick up the gernade but do not throw it. Go to sniper mode and hit the ball in the doorway that keeps you from getting through it. This will cause Dr. Hawkins to stop talking and will take away the gernade from your inventory but it will make Kurt invincible! Well worth it!