Well, first you belittled your daughter when she liked it, and now you love it which makes for some confusion on her part, and so now she is doing the same thing you did to her... so you feel like now that you like it, she should just forget the way you made her feel it was stupid too?
I don't know, it's a tricky thing. I mean, if my mom was all over New Kids on the Block when I was a kid, and carrying around a New Kids purse and bath towels and stuff, I would probably have been embarrassed too! Are you going to be throwing a Hannah Montana party as well? Just curious.
For one, you have to respect her first and show her that example. Then, you have to consider that maybe she has a point. I mean, I don't know if you're dressing like Miley and dancing around the house in boots listening to the soundtracks, or watching the movie every week and crushing on Billy Ray, and gushing over Miley/Hannah with your daughter's friends or anything, but if so, then your daughter has a point, and maybe you should be a little more reserved about this, at least in your daughter's presence. I mean really, Miley isn't exactly a stellar role model for teens or young girls anyways.
Still though, there is that line of respect she needs to be giving you.
Really, you just need to sit down with her and explain you have your likes and she doesn't have to like that, but you are still her mother and she needs to remember that and treat you with respect. If she continues to mouth off or get nasty with you, ground her, take away her cell phone, she has to miss going out with her friends, do extra chores, loss tv/computer priveledges... make her write an essay on respect (what my parents made me do).