Moving Library causing Deletions?

Question

I've been reading through posts here and it looks like maybe there is a problem with the new iTunes upgrade. But I don't know if it is the same problem I just had.
I have an intel Mac Mini with 10.5.4 connected by firewire to a non-intel Mac Mini with 10.4.11. My iTunes library is on the non-intel Mini, but I play it through the intel Mini having chosen the library on the old machine as my default for my intel Mini installation of iTunes.
After having gotten the logic board replaced on the intel Mini, I went to move a smaller iTunes library off the intel Mini onto the main library on the old Mini (about 600 songs). I did this as follows: I accessed the library on the intel-Mini, selected the folders in the iTunes library and dragged and dropped them to the user library on the old Mini -- it puttered along and then the finder (on the intel Mini) froze. I restarted and now about 1200 songs are missing off the old Mini (both "purchased" and not and I can't find them).
1) The songs deleted weren't the songs I was moving.
2) I have iTunes 8.0.2 on both the intel mini and the old mini
3) There are also some odd problems when I am accessing my library (located on the old Mini) through the intel Mini:
i) it says it's not authorized to play any purchased music (which it never had a problem before the logic board was replaced)
ii) it won't let me pick "Album" as a list category -- it always defaults to "Album by Artist"
iii) some songs it says are gone from the intel Mini view of the library are there if I am accessing my library directly on the old Mini (but not all of them)
I don't even know where to start looking. I tried "spotlight" and it's not finding the songs. Where could they have gone? Anyone have an idea what may have happened here and why?

Answer 1

Thanks for the reply.
I'm on my computer (Windows machine) at work so I can't look up exact directory names/paths on my Macs. But what I mean by "library" is the directory in my user directory which I think is called "iTunes Library" which has inside of it a bunch of subdirectories with music files. I realize changing this doesn't change the library .xml file which I assume is what the computer accesses to display the listing of songs when you have the iTunes window open.
Previously, I had "imported" the smaller library (the one I was trying to copy over) from the intel-Mini to the main library on the old-Mini from within iTunes. Except when the intel-Mini was in getting its logic board replaced, it became apparent that all that was "imported" were some sort of indexes to those files because they had not actually been moved/copied to that other hard drive. When I got the intel-Mini back, I thought I could get around this by just copying the subdirectories directly instead of "importing" them. I'm not sure why I thought this wouldn't be a problem for the .xml file.
I will try that "click through" option for the "Album by Artist" thing. I've only tried selecting the view option (for the columns that display in the iTunes window) for it to display "Album" but I always get "Album by Artist" -- I haven't specifically tried repeatedly clicking that column to see if it changes into just plain old "Album"
I suspected that the new logic board might make this a "new" computer. Because I set the "library" in the "Advanced" setting in iTunes to the library on the networked computer, I didn't think it would need authorization (I don't remember having to do that the first time I set up this connection) because, I thought, technically, the library is still located on the drive where everything is authorized.
But I guess, the real questions are: 1) is it NEVER safe to just copy those subdirectories? and 2) is there any way all that music isn't really gone?
I can probably restore most of it from my CDs and my last "Purchased Music" back up (which isn't entirely up to date), but the bigger problem for me is identifying just which files are gone without having to scroll and select through several thousands songs from the library list.
I'd take any advice . . .