What do you do if you still have issues when connecting with a new iTunes library?

I have been having issues when connecting my iPhone 6 to my Macbook Pro (early 2009) - currently running the most up to date software. Overtime I plug in the phone iTunes recognizes the phone and then immediately freezes/hangs/I get the wheel of death. I don't have the issue when I log into the computer with a different account, but I still do have the issue when I log in to the computer under my normal account with a new iTunes library. What do I do now? Is there something in my music file that is causing the issue?