So... I have a staff member who is intent on discrediting me. When I am out of the room she attempts to engage other staff in a bitching session about me. She has shouted in my face because I asked her to change the way she is working to be more in line with school expectations. She has refused to come to some meetings. Twice in the past week I have overheard her talking about me in a less than professional manner. When we have new starters the first thing she does is run to them and try to convince them I don't know what I am doing. I have put up with it for 2 years now, attempted to turn a blind eye and hope that given enough rope... But now I have had enough. She is causing a bad atmosphere and she needs to grow up. How would you approach this?