The disappearing music just started happening to me.
Two days ago, I was editing some album info, and got a popup message "Are you sure you want to edit multiple items?" I didn't think anything about it, but just selected "yes".
Suddenly, stars appeared in the Album by Artist field, then
POOF.. almost all of my library disappeared from the playlist and from the iTunes folders. I went from over 1400 tunes to 31.
Here is a (size reduced) screenshot of what I had left. Note the weird stars that appeared in the wrong column.
http://dl.dropbox.com/u/144430/iTunes_fiasco.jpg
This morning, the same thing happened again, only this time ALL the music disappeared. It happened (again) while I was editing (fixing Titles, etc).
I've restored again, but this is unnerving. Even more unnerving to find that it's a known and ongoing issue.
I thought I was going to come here to the forums and find that I needed to throw away a preference or something similar.
It is very strange to find that it's something this serious and hasn't been addressed yet by Apple.
Very freaky, easily restored via Time Machine, but.. DAILY?!
sheesh
Message was edited by: m1ck