Steve, I agree with Jim that your daughter is going through a transitional period, and around her age is usually the time they push back against their father and bond more with their mother. My two daughters are grown now but I went through it with both of them and it was difficult, confusing and stressful. A book that I found helpful was "Yes, Your Teen Is Crazy!" It goes into the physiological changes that teens go through and how it can lead to erratic, unpredictable, totally out-of-character behavior. The good news is that it usually is just a phase and if dealt with properly will actually improve your relationship.
As a side note, I can't stress enough that "dealing with it properly" is critical. I have a good friend that had a daughter that thought he hung the moon, and he in return would do anything for her. She went through this rebellious stage and he completely shut her out of his life. She is grown now, happily married and has a child. They never did fully repair their relationship. You've got to be firm with her but you have also got to be LOVING. She will fight your love every step of the way while inside being grateful that you never gave up on her.
