iTunes Match reboots my computer
First, the technical specs:
Model Name: iMac
Model Identifier: iMac13,2
Processor Name: Intel Core i7
Processor Speed: 3.4 GHz
Number of Processors: 1
Total Number of Cores: 4
Memory: 32 GB
Boot ROM Version: IM131.010A.B05
OS: Yosemite 10.10.3
iTunes: 12.1.2.27
My iTunes library is located on an external LaCie 3TB Thunderbolt drive.
For some time I've been trying to determine why I could not get iTunes Match to work properly when syncing with my iOS devices (an iPhone 5 and iPad 2 (maybe). Both are on iOS 8.3. After much poking and prodding, I realized that the issue was due to my having over 35,000 songs in iTunes. I spent a lot of time paring down my library until I got down to about 24,000 songs (this includes the 200 or so purchases on my Apple ID, so I should now have plenty of buffer).
I also wiped out the iTunes Match data from prior syncs by clearing out my library then deleting the songs that iTunes indicated were up on Match. I wanted a fresh sync of data.
However, every time I try to launch iTunes Match, whenever I get about a third of the way through Step 1, my Mac reboots. It appears as if Yosemite freezes, but instead of the grey screen of death, the computer just reboots. I've tried looking for crash logs, but there is nothing I can find. Even though I am not an expert by any means, I can usually find the crash log or even the entry in some log somewhere I can grab a screen cap of to send to the more tech savvy. But right now it looks like nothing's getting recorded and Yosemite is treating the reboot as just that: a reboot.
In my attempts to troubleshoot, I have reinstalled Yosemite, reinstalled iTunes, deleted and rebuilt my iTunes library database. I've run Disk First Aid on both my boot drive (through recovery mode) and my Thunderbolt drive. I've even re-imported every song, twice, and culled any file that caused an issue on import. I've scoured my collection for not only absolute duplicates, but also, when the choice came between a song contained in a full album and a song in a partial album, I deleted the partial album's file.
At this point, I've run out of ideas on troubleshooting. Well, maybe not quite. The only variable I did not check out was the presence of my husband's purchased music. Ideally it should be ok, since we linked our accounts (through the family feature). Yet this was a newer feature and this is the first time I've tried to re-sync iTunes Match from scratch since the Family feature went live.
In any event, any suggestions or advice would be most welcome. I rather enjoyed iTunes Match, and am loathe to give it up. Yet I can't see paying for a service that won't work. If you need to look at logs, I'll be happy to provide. Key words to look for would help greatly.
Thank you.
Edit: I also repaired permissions as part of my troubleshooting.
Edit: I removed all purchased music. I also deauthorized and reauthorized my iMac and logged out of and back into my account (I only have one account). iTunes Match still stalls about ⅓ of the way in to Stage 1. I stopped iTunes Match from processing right now.
iMac (27-inch, Late 2012), OS X Mavericks (10.9), 3.4 GHz Intel Core i7 32 GB DDR3