I'm really pissed at myself, I'm not sure what my problem is, it's not what most people are describing as in social anxiety or fear of rejection, I just back out of going to talk to girls that I really want to talk to, and I make up lame excuses to myself of why I can't, I would consider myself very desirable and I'm confident all the time in every other part of my life so I'm not really scared of rejection, I'm a total alpha male at work and with my friends, It's got me total baffled, It only seems to happen when I have a girl I specifically want, I know that I can get a lot of other girls, probably better looking ones, I commonly flirt with and have no problem with talking to random girls, but it's when one specific catches my eye, I suddenly become deathly afraid of talking to her, I feel like I can't do anything about it, (I know I can), I literally was swearing at myself and telling myself to go back as I was leaving without talking to this girl, but my body wouldn't listen.

I know exactly how you feel. I got lucky though and met a girl like the ones you describe who "catches you eye" who I felt so incredibly comfortable with that it wasn't a problem at all. So I guess what I'm saying is you just gotta meet the right girl.

Im going through the same problem at the moment but Ive got some one to one online help on this and its a need to Detach yourself emotionally from the outcome of any interaction you have with any girl you feel like this about.
You enjoy the want of this girl in your mind but you must detach yourself in the real world and just let whatever happens happen and think its just the way it should happen.
Due to the laws of attraction, give her a chance for the desire to manifest itself into a real and tangible result naturally.