I haven't backed up my iPad with iTunes in a long time. I'm now trying to back it up, particular the apps on it. The problem is when I plug the iPad in and launch iTunes, I get this message saying my iPad is synced with another iTunes library. My only options are to "erase and sync" or cancel. I don't know what is in that "other iTunes library" and I surely don't want my iPad erased. What is this other iTunes library and how do I get rid of it so I can backup my iPad without it getting erased? Thanks.