From a political viewChad Aaland,
If you could try taking to her and tell her why the way she is working interfers with your work.
Tell her in a nice way and dont forget to mention that it would really help you if she would change some of her habbits.
Dont forget to mention her that you are helping her to lift things for her.
You can also ask her to help you for your banquet in return since your are cleaning up for her.
I think this is a very nice way to take care of this problem. also try to fix this problem by finding a solution that is beneficial for the two of you, a win/win solution. Because right now you are in a lose/win situation and she seems to be on the win side.
however, if you decide to turn the table around and be on the win side and her on the losing side, she might want to turn the table around again, and this little conflict could grow and become an intestinal war.
one last tip, every decision you make when solving a conflict, must be perceived by the majority of the employee (superiors, co-workers...anybody in the joint) as the best solution. the reason is simple, if you solve this problem by making this a win situation for you and a loosing situation for her and this becomes an un-popular way off seeing this conflcit solved, your image will suffer and you will have more people against you.
The solution you will find must reflect what the majority of the people in the enteprise finds accepteble and the solution you will find must be defendable on the all ethical point of view.
I hope I this will help you.