She sounds like an annoying twat! (sorry to be blunt). But i've experienced this myself and it is really frustrating.

Some women, no wait, Most women...no actually, ALL women love attention and they will take it from anyone offering it (even if their not attracted to him/her/it). This one in particular is enjoying the the fact that you're into here and is milking you for your attention by giving you flakey responses that will create more questions then answers.

My advice would be to stop interacting with her. But im going to add to it... instead of just stopping the interaction, i think you should stop on a high point. but, YOU need to be the person to break away...

Edit: I agree with Refl3x on this one... move on shes a waste.

Peace,
Y45