OK, I'm a secretary and she sounds like a bit much, BUT, a lot of times the people we support have no clue what is really going on in "our world" and how we get things done.
Is she YOUR secretary, or is she the secretary for the company - and therefore might have reasons to be in the boss' office for half an hour doing things. I find it odd that you have a secretary BUT you are also in a position where a secretary could take over your job if you left tomorrow.
I'm sorry I sound bitchy, but we've been having issues with the people we support being really obnoxious in their demands lately at my office, so I might be a bit sensitive. I'm just trying to determine if you just don't like her, or if she's really a bad worker. There's a partner here I hate and would lock in a closet all day every day if I could, but the clients like him and he gets the job done, so he's staying!