My wife has an iPod Touch and she manages her own music library on our PC, but occasionally I’ll purchase a couple of TV shows on my computer (a Mac, but that shouldn’t make a difference) and put on her iPod for some in-flight entertainment.
Before we left I bought a couple of shows (Dexter, if anyone’s interested), and manually added them to her iPod. In this case I was logged onto iTunes using my own account. I had automatic syncing turned off and had no problems. For our return flight, I bought 2 more episodes, but in this case I logged on to I tunes using my wife’s account because she had some iTunes credit to use up. However, when I tried to add them to the iPod I was told that I couldn’t because this computer wasn’t authorized to play those files. I relogged on to iTunes as my self and it still didn’t work. I then tried authorizing her iPod from the Store menu. This allowed me to add the new TV episodes to her iPod, but also proceeded to delete her entire music library (luckily her library is on another computer, but she probably would have liked to still have it on the iPod for the flight). Any clues what I did wrong and how I can avoid this in the future? Thanks!