I am supposed to be doing my homework right now but my little girl is driving me nuts

She is under my chair and she won't stop growling.
Ok this is why... My little girls HATES my son!! I know, I know, hate is a strong word but it's true. If she could, I am convinced she would tear him limb from limb!!!
He is not being malicious but still!! He is 6 years old and FULL of energy. He will run down the stairs or jump off the couch and it scares her. He doesn't do anything to her personally.
So now of course anytime she hears him she starts barking like crazy!!!! If he is sitting on the floor watching TV and she hears a noise she will run over to him and bite him. She has even drawn blood twice
I don't know what to do because I reprimand him at times for scaring her when it probably should be her that is having the time out
He has come to hate her!!!!!! I will NOT,NOT,NOT,NOT, be without my dog, but I don't know how to stop the behavior on both parts (skin and fur).
Help what do I do???????