After a second viewing, it all comes together beautifully - SPOILERS

Rating: 10/10 (27 December 2001)

Mulholland Drive is the best movie of 2001. It is also the one which takes the most time to figure out and the one that needs a second viewing to truly be appreciated. Here is my interpretation of the meaning:
HEAVY SPOILERS AHEAD
Everything, up until the point when Diane Selwyn wakes up in her bed, is a dream. That brief opening shot of a woman in bed is Diane and the first 2/3 of the movie is her dream. There is no Betty, except maybe a spirit inside of Diane that died long ago. When Diane wakes up, the "real" movie begins. Her lesbian lover, Camilla, has decided to settle down with Adam. This further scars Diane, who hires a hitman to kill Camilla. She is tormented by guilt after it happens, though, and she shoots herself in the head at the very end of the movie. Then, the story of a fatally disenfranchised woman comes to an end with the word...silencio.