I have a large iTunes library, the majority of which is ripped from CDs. Around 2000 files (out of 6000) are no longer playing (as of last week). When you double click on them, the area at the top of the screen with the time display just shows an apple logo, and the speaker icon doesn't appear to the left of the track. In finder, viewing the file info shows the correct file size and track time, and will display all the ID3 data, yet the preview function will not play anything. The affected files are a mixture of AAC and MP3. I have recreated my iTunes library, but it will not add the unplayable files back in. I have read the following from the Apple help pages: "You might be trying to play an AAC file that was not created using iTunes or downloaded from the iTunes Store. Songs you download from the iTunes Store or import into your library using the AAC encoder are encoded using the new MPEG-4 AAC format, and play in iTunes and on your iPod. Other AAC files that you find on the Internet or elsewhere won't play in iTunes." However, all the music was encoded using iTunes. When using Front Row to play the music, it says "Your computer is not authorized to play this song." Has anybody come across this issue, or know anything about it? I've searched endlessly on the internet to try to work out what is causing the issue, but with no luck. Any help would be greatly appreciated - it has taken me many years to digitize my music collection, so this represents a huge issue for me. For reference, I am using a Mac Mini 1.83ghz, with 1gb RAM. All the affected music is on an external Hitachi 160gb PATA IDE hard drive running in an enclosure for internal disks, connected through Firewire.