Question (Transferring library)

[Nemss316]

I recently built a new rig at home. So I followed apple's instructions, copied my library on to an external, and then transferred to my new PC. Me and my g/f authorized the new computer. I plug in my iPhone, and I cannot add music It says that this iPhone "belongs to another library" and asks if I want to restore. So, now I cannot add music to my iPhone, but I can transfer purchases from my phone, etc. I just can't add music.

I can play all of the songs that I purchased, but when we try to play songs that my g/f purchased, it constantly asks for her username and password to authorize, even after she did authorize the computer.

Any ideas? I really don't want to do a full restore on my iPhone to put music on there, and I cannot figure out why we can't play music that my g/f purchased!

Thanks!