Itunes, ID3 tags, & hard drive corruption

Question

My wife is having a strange problem with her iMac, and it’s got me a bit mystified. I’m hoping someone here can shed some light on what might be going on. I apologize in advance for the long post.
The problem is that when she plays some songs in iTunes, and entirely different (wrong) song plays instead. Most songs play fine, but some just play entirely different songs (or sections of a song or podcast). All of the tracks are MP3 (either 192 kbps or 256 kbps) and almost all of them were encoded using Windows Media Player on an XP machine. Initially, I copied the music over from an NTFS drive to a newly formatted (Mac OS/HFS+) drive on the Mac, then I ran iTunes and created the library. At that point, everything seemed fine. All the meta data (song title, album title, artist, album artist, genre, album art) showed up in iTunes, and everything played correctly.
Now we’re getting this weird behavior where we play some songs and get the wrong music. At first I thought the iTunes library files (ITL and/or XML) had been corrupted, but it seems on closer inspection that the entire hard drive has been corrupted. When I look at the files on Mac hard drive via the Finder, all seems ok – the directory structure is intact, the file names and sizes are all correct, and a Get Info on any MP3 file shows that the ID3 data is all there and seems accurate. This is true even for the songs that play wrong, but if I play one of those songs using the little mini player in the Get Info dialog, the wrong song plays (the same wrong song as in iTunes). So now I’m getting the behavior straight off the drive, with iTunes closed and the iTunes library completely out of the equation.
Some other interesting clues/evidence:
* This has happened before. When her first hard drive got corrupted (in the same way), I was mystified but chalked it up as a bad hard drive and got her a new one. Then we started over with a clean HFS+ formatted drive and clean music files and built a new iTunes library. And now the same thing has happened again. So I don’t think it’s just a bad hard drive.
* It seems to be progressive. That is, everything was fine in the beginning, but over time more and more files get messed up. We know this because we have a backup that’s about a month old on which we can locate files that are fine (on the backup) but that are messed up on her connected day-to-day drive. So it seems like some activity on the drive is causing problems that are growing over time.
* There is some weird meta data (ID3) behavior. I copied a few hundred MP3 files from the Mac drive back to the PC (over our home network) and looked at them in the Windows Explorer. The first thing I saw was that the same (wrong) music played for the bad tracks as had on the Mac. And I also saw that a lot of ID3 tags were not showing on the Windows side. Lots of tracks have no ID3 data (album, artist, genre, etc. is missing) when I look at them on the PC. There are many albums where tags show up correctly for some of the tracks but not for others. In fact, the number of files where the ID3 tags aren’t visible on the PC far exceeds the number of songs that play incorrectly on the Mac. When I look back on the Mac at the songs that have no ID3 data on the PC and do a Get Info, I see the ID3 data.
* Often, though I can’t say always for sure, the wrong music that plays on the Mac is stuff that has been recently added. Either podcasts or music that my wife has added since the initial library was established.
My best guess (though still full of holes):
Something is confusing the Mac OS into writing on top of occupied space on the hard drive or into mapping files incorrectly in the drive’s allocation table, and chaos results. The Mac doesn’t think anything is wrong, and it shows everything as being clean in the Finder. So I started thinking about the kind of reads & writes my wife is doing on that drive. She rips new CDs to add to the library, she downloads new Podcasts and deletes old ones, and she changes ID3 tags.
I’m focusing on the changing ID3 tag activity. My wife doesn’t like the way I tag genre. I like big broad categories, an she likes smaller, more specific categories. So she has gone through the initial library of 42K+ songs and changed the genre on thousands of songs. She’s change some from Pop to Power Pop or from Pop to Indie Pop or from Rock to Indie Rock, etc. Both WMP (where the tags were created) and iTunes support ID3v2.3, and so these two programs ought to be able to change tags in a totally interchangeable and safe way. But what if iTunes writes its new genre tags in a way that’s slightly different from WMP? Could iTunes be writing to memory/disk locations that are outside the boundaries of the file and thus creating some kind of buffer overrun?
It really doesn’t make a lot of sense, but it does tie back to the evidence that this has something to do with meta data, gets worse over time, happened on more than one disk, and seems to be a file allocation table issue.
Even if I get to the bottom of this, I think my wife’s HD is toast for sure. Here’s what I think I will do: I’ll reformat the drive, re-copy the music over from the PC, and build a new iTunes library. Then, first thing, I’ll open iTunes, select all the songs in the new library, and run “Convert ID3 Tags” to ID3v2.4. If that works and everything behaves correctly, I’ll try to change some genre tags and test the results. The problem is that the library is so large that problems can go undetected for a long time, so maybe I should do this first with a small subset of the music as a trial run.
The thing I want to avoid is having to do this (ever) again, so I’d feel more comfortable if I understood the bug/problem before just following this guess (which feels like a roll of the dice). If anyone has seem similar behavior or has heard of any IDS incompatibilities between WMP 11 and iTunes 7, I’d love to hear about it. Any help is appreciated.
Jim

Answer 1

Wow, that was a long and detailed post. I haven't the energy to reply in equal fervor, but I will just say that lately these boards have been peppered with posts from people whose MP3s are being eaten alive by iTunes. What I don't get is why you suspect the hard drive is at fault. Unless the rest of the system is caving in, I don't think there's any reason to suspect a failing drive. Check the S.M.A.R.T. status in Disk Utility if you haven't already, and perform whatever maintenance you believe is in order.
For the most reliable ID3 tag editing, I'd certainly recommend using foobar2000 on a Windows PC (or a Mac with Windows installed) or MP3Tag. I would definitely, at least for the time being, not put your huge music collection at risk by doing any further editing of the tags in iTunes.