Normally, assuming no changes have been made to what is being synced, this should take a matter of seconds. Except this time, something unexpected happens. iTunes begins copying several hundred files to your Apple TV. No error message or warning appears. The files just copy as if you had newly added them to Apple TV's playlists. This is especially odd because you recognize these files as ones that have been previously synced and should already be on your Apple TV.

Depending on how much data needs to be copied, and the speed of your network connection, this recopying can take from minutes to hours.

Making matters worse, the exact same thing may happen again and again, as often as several times a week. It probably doesn't happen every time you launch iTunes. But often enough to be really annoying.

How do I know all of this? Because it's happened to me. It has also happened to numerous other Apple TV owners, as described in an and a .

The recopied music appears to be DRM-protected music. The consensus theory is that somehow, at some point, either Apple TV itself or iTunes is blocked from connecting to the iTunes Store. Without this connection, there can be no confirmation that you are authorized to play the protected files. The result is that the files are deleted from the Apple TV. When you next sync Apple TV in iTunes, after iTunes Store access has been restored, the authorization is recognized and the files recopy. In my case, a temporary loss of Internet access from my cable modem appeared to be the triggering event.