Every time I open iTunes on my Macbook and hook up my iPhone, a message pops up saying that my iPhone is currently synched to another iTunes Library. The message asks if I want to synch this iPhone to this library but the contents on this iPhone will be erased (I then click on OK so it will synch, which erases all my music). I then have to have all my music copied back over to the iPhone. I only have one iPhone and one copy of iTunes on one Mac. Why does iTunes keep telling me that my iPhone is synched to another iTunes library every time I want to copy over music or podcasts to my iPhone each time connect it to iTunes? In the Menu bar I clicked on Store, then Authorize Computer thinking that would help, but it says this computer is already authorized, so that didn't help. Thanks for any help or suggestions.