I upgraded to iTunes 4.5 and QuickTime 6.5.1 from iTunes 4.2 and QuickTime 6.5 under Mac OS X v10.3.3. While the install went smooth, I noticed an extreme slowdown in my system after launching the the new version.
Activity Monitor showed iTunes 4.5 grabbing all available CPU cycles, so I quit and relaunched and after a few seconds I ran into the same problem. Remembering a tip from Trollaxor over at MacSlash, I ran sudo diskutil repairPermissions / in Terminal.app. While a lot of file permissions were repaired, this changed nothing with iTunes so I rebooted. This is where things get sticky.
I relaunched iTunes 4.5 and it spent a good five minutes updating my library (which means what specifically I don't know). After that iTunes was speedy, but my music was destroyed—over 10,000 tracks of carefully downloaded or ripped songs that took me three and a half years to make! I think I should probably explain how they were ruined, though, since I've never seen this before.
All of the songs have some hissing or buzzing in them now, similar to the sound of playing a data CD in an old CD player. Most of the tracks also overlapped with other tracks. It was as if iTunes had created new MP3s out of several old ones. Another detail to note was that several of the song files and ID3 tags had been renamed to garbage that looked like someone had held down the option key and jammed their hand randomly on the keyboard.
Has anyone run into this yet? I don't see anything that I did wrong, though I'm no expert. Did I perhaps run a wrong command for the Disk Utility program? If so, I am going to be pissed. But I've done that command a few other times and nothing has ever changed. So I'm stuck here and am hoping there's some way to fix my music files and regain some faith in iTunes, Mac, and Apple after this disappointing bug.