How to deal with a micro-manager who ISN'T your boss??!!?

I work for a small recruiting firm and my boss is an egotistical, hot head BUT he is respectful of me and has not yet crossed the line as far as respecting me, my abilities and allow me to do my job. I handle all of the scheduling for the office and I handle his calendar and everything else for him. HOWEVER, one of the recruiters that I work with has crossed the line a bit in terms of how she interacts with me. She started micro-managing everything I do and is swift to point out if I overlook something or make a mistake. I own up to my mistakes and am accountable for all I do. However, it is just driving me insane how anal she is and just want to tell her to back off and let me do my job. My boss is also very anal and the process in which he has me doing things is redundant and some things aren't necessary. It causes more confusion than it's worth. I wanted to get some thoughts on how I should handle this and if I should say something. I have owned my own business for the past several years and recently returned to a regular job outside the home. I do enjoy most of what I do, but these people are driving me batty!! 7 people have quit since I've started less than 5 months ago. This should be a very clear sign!!