Diane/Betty was a professional dancer but had a terrible accident - damaged her knee.
And can't be a dancer anymore.
Her parents didn't want they daughter to be a dancer, so they gave her money to begin her life in LA.
They persuade her to become an actress in Hollywood and be a star in big screen movies.
So Diane/Betty thinks they are happy because of her damaged knee (her mother poking her husband in knee and they are sharing diabolique smile in limo).
Diane/Betty is going to LA and she is looking for a role in film.
She was terrified going to auditions and nobody is calling to hire her as an actress.
To feel not so lonely, she developed fictional friend - Rita, who looks like an actress Camilla Rhodes whom she met.
Camilla help her and Diane/Betty played as extra in one of movies in which Camilla was a star.
Diane/Betty has found film agent - Joe, whom she pay a lot of money for find the part in film, but she get only minor role in TV show in which she should to play a dead body.
She's depressed and broken because she spend all of her money only to play a dead person.
She imagine her parents despise at her when she return to home to them without success in films.
And Diane/Betty now have no choice - she's killing herself to play a dead body in TV show (Twin Peaks).
Blue box is a symbol of television.
Blue key open career in television.
Did you know Sheryl Lee was a dancer in the past and was a knee injury. After that she was not able to professional dance?

What do you think about this theory?


(sorry for my poor english)

Hi razfan,
interesting point of view.
But I don't really see the clues for your theory.
For every claim there has to be a proof or a proper argumentation.
Some things in your theory seem to be too far-fetched to me.
Did you read the 10 clues David Lynch gave us in the case of the DVD version?
It's really clear that the movie is about the relationship between Diane and Camilla.
The Club Silencio scene is the turning point of the whole movie.
Betty becomes aware that it's all just a dream (you can see her fall to bed in the beginning of the film).
She knows she has to go back to reality (the blue box) and then wakes up as the real person Diane.
Don't you think the old couple is too old to represent her parents?
She didn't just meet Camilla, it's clear that they had a relationship and Camilla wants to hurt Diane when kissing and engage with Adam.