What strikes me in the story. You tell her to get out of the room. She's hurt and responds by telling you to get out. That says to me that whatever the reasonable intent in telling her to get out of the room she heard it as a rejection and she followed your modeling to the same behavior.
I can guarantee it won't work 100% of the time, but my suggestion would be to focus on giving her positive roles and working with her in advance about transitions...
So, in the dining room example, I would suggest involving her in the planning of the job. What parts can she do, what parts can you do, what will be your plan to celebrate when the job is all done? Could she go in the next room and help pick out the cleaning music? Would it be possible to set the timer for ten minutes for the part of the job you have to do alone and while you are working on that part could she get the dollhouse set up so you can celebrate your hard work with some fun time playing? Could you break down the job into five distinct phases and celebrate finishing each phase with a cheer? Could she be allowed to do something particularly exciting or challenging as our helper (technology like the dustbuster has been appealing here).
This sort of approach has worked well for our family for a few reasons. First, it appeals to the child's natural desire to be included and develop responsibility. Second, it keeps us in a positive place where we feel like we are working as a team. Third, I rarely have to say anything I don't later want to hear coming back out of my child's mouth. If I had to say "you go in the other room and leave me alone" I know I'd be hearing that back later. I don't mind hearing back "hey let's make put on the music and clean this will be fun" back later. What we model we hear back later.
