Can't stop thinking about a lost cause

Okay, long story short there was this girl who I liked. Ended up not working and I have already gotten over her, even tried 2 more times (with 2 other girls, both ended the same, lol...sigh).
For some reason, unknown to me, she keeps popping into my head. She enters my subconscious thoughts. A week ago she was in one of my dreams.
I do not like her anymore. I have gotten over her (basically, she isn't my type any more).

My question has 2 parts...
Why do I still think about her?
How do I stop thinking about her?

Why: because your mind hasn't accepted yet it's over.

How: have your mind accept it's over.

not sure what else I can do to get over it, if that truly is what is wrong.
The thing I hate the most about her is that she smokes, there are many other reasons but that is the one that stands out.
That song, "I hate everything about you" by three days grac sums it up. I don't even have feelings for her. Everytime she appears in my mind I have feelings of disgust mostly, the fact she is a pot-head disgusts me, knowing I was into her disgusts me even more.
I guess my mind could still be thinking of the one that got away, then why am I not thinking about the more resent attempts, or my first love? How about thinking of the girl I am planning to ask out? (I am planning because I want to drive her up to the AMC theatre but I have not driven up there yet and need practice to be comfortable doing so).
I guess I am just trying to understand human nature here. I am an anylizer, so I have used her as a referance on the most recent girl i was into (which prooved to be useful). Would that explain it? Is she just a referance for me to judge by? If that is, is that a good thing?

I apologize for my long rant. I just have a million things going through my mind right now, just slightly more than the 999,000 usual.
Its typical of questions like this though. Ask a couple questions and the answers lead to more questions.

Wow, maybe you were just meant to be. You may never love again actually, this is probably your one true love. The only thing I can suggest is to check your horoscope and see what the stars have in store for you next....
Are you crazy man? Look, you need to snap out of it. There's one reason she's on your mind, and that's because you want her there. Probably because you're the hopelessly romantic type of guy that sums up his emotions by referencing popular songs. Not that there's anything wrong with that, lot's of girls dig it, and I would suggest putting those qualities to use on one that does.
Also, if you want to know how to stop thinking about her, and simply deciding not to think about her, I would suggest boosting my testosterone level by lifting weights, playing sports, or having lots of sex.

OBVI! you're not over her, she's still your type, and your kinda sad. However, KNOW THIS: You WILL eventually get over her. Stop fighting it though. Admit you liked her, still do, and then wait for the feelings to dissipate. THEY WILL. When they do move on and do "you time" and when you meet someone else the same pattern should not happen. If you still can't stop thinking about her, you may need some professional help... did she remind you of anyone else in your life? Like your mother? thats some sick stuff ... I kid I kid... no really...

On a more serious note, I really agree with keepitreal also. Way to keep it real keepitreal.

ok. let's try a different technique. let's say you own a really nice car. so you buy it, drive it around for some time, and then while parked outside, a hummer basically drives over it, totalling her. now you don't have the finances to fix it, but will you ever forget it? probably not. same goes for women.

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keepitreal, I guess your right. I do still like her even though I hate loving her.
She is my type but certainly not an ideal match.

Il Cattivo, (first post), Honestly it disgusts me to think that I once thought that was true. Infact, it was true but that changed with age as she was ideal in 8th-9th grade. I blame my feelings for her on hormones (vile things they are).

Indignant, this is the first time I will agree in a comparison of cars and women. For the most part, the woman is important and the car is just the transportation to and from a date or where ever.

I did notice that the first girl after her that I seriously tried with (almost got to asking her out) I never thought about her. The seconde girl I seriously tried with, I only remembered the lost cause because I noticed similar signs that told me a failure was inevitable but I still went through with it until I was rejected (which felt good knowing I could tolerate it or that I went through with it). I figure that being serious is like my medication to not thinking about her.
I am going to accept she is in the past, I am in the present and my future will not involve her.
I just need to stop picking at this scar and let it heal already.

Edit- Il cattivo, I don't care to lift weights. I self train in a martial art style but have not been able to recently. And I am not going to have lots of sex. Adrenaline should do the trick, Worlds of Fun, here I come!!! Actually that may help my friend to feel better, (going through a tough time, post is in the 'ask a female' section, take a look please).

anyway, thanks for the advice. I was getting annoyed about it, now I think I can handle/fix it.