Pat,
**spoilers ahead, for any who haven't seen it**
my take on Mulholland Drive is that both halves (I am defining the middle of the movie by the place where the actresses switch roles) are simply fantasies of the main character.
A little bit of reality is shown, but mostly fantasy.
The creepy part of the movie is when the 2 ladies go into the apartment of Diane Selwig. (is that the right name?) Anyhow, this scene, near the end of the 1st half, is foretelling what will happen to the protagonist. She will die of an overdose and no one will find her for days.
The blue key is shown as both a fantasy key (the star shaped key opening the magical box) and a real key (a simple key painted blue).
In the second half, the guy who played the hitman in the 1st half is a drug dealer. He deposits the stash somewhere safe (not shown) and brings her the key, leaving it on her table (shown) so she can pick them up.
The drugs both enhance and destroy her fantasies. That is why, in the 1st half, the dealer is depicted as a hitman out to kill the sexy amnesia woman. (I forget if she is given a name)
The sexy woman may or may not represent a real person, but it is clear that she becomes one of protagonists fantasies. I think that the protagonist at the beginning is also playing a fantasy role, so in the 2nd half she reverts to a waitress.
All I can say about the masturbation scene is... wow! That was so intense and painful at the same time.
Hope you enjoyed the movie; I sure did.
cellomould
"You're crying 'why am I the victim?' when the culprit is YOU" Stevie Wonder