iTunes is hanging and flickering after logging in. Anyone know how to fix this?

Hi all, I just got an iPhone 7 (iOS 11.1) and I connected it to my PC (Windows 10) and then ran iTunes as administrator. When it loaded it asked me to sign in with my Apple ID and pw, so I put them in and pressed "enter" or "next", and then the iTunes sign-in window hangs and just flickers, and iTunes is unresponsive. I could close it via Task Manager. I tried several times, and I also tried updating iTunes, as well as restarting the PC. iTunes was/is up to date. Just FYI, the phone's OS was 11.0 (or whichever is factory installed) when this happened. One of the things I did in hopes of it making a difference is update the phone to iOS 11.1. Nothing changed. Other than uninstalling and reinstalling iTunes, I have no idea how to fix it, and I am afraid I might lose my music library. I can't make any changes in iTunes (there's an option to back up the music into a folder, I think, but I can't tell if that was already checked). Can anyone help? Thanks in advance!