About approaching a boss (or anyone for that matter) on a sensitive subject, I highly recommend this book. I just finished it and it was an answer to prayer for me and it sounds like it could help you deal with your boss.
Crucial Confrontations: Tooks for Resolving Broken Promises, Violated Expectations, and Bad Behavior
Authors: Kerry Patterson, Joseph Grenny, Ron McMillan, and Al Switzler.
It's well written, highly readable.