Seems to be a common recent iTunes problem

Question

In searching the forum, I've found a few people experiencing this problem, but no solutions...perhaps someone has come across a solution?
Yesterday, iTunes informed me that my Library file was damaged, saved it under a different name and opened a new, blank Library file. What's more, quitting iTunes and restarting iTunes replicated this behavior: the new, blank Library file was found to be "damaged", it was saved again under a different name and yet another Library file was created. And so on.
Further, I found I could not re-import my music.
Here is some data about my Mac:
iMac G5
1GB RAM
OS X 10.4.11
iTunes 7.6.2
Quicktime 7.4.5
My iTunes music and video files are stored on an external firewire hard drive. Here is a history of what I've tried since I discovered this issue:
--Tried re-importing the music from its current location
--Backed up music to a redundant external drive (not enough room to do so on my primary hard drive), tried re-importing the music from that location
--Saw that the original location needed disk repair; wiped it clean and moved the music back and tried to re-import.
--Reset iTunes to look for its library in the default location on my internal HDD, copied a sample of my music there and tried to import it.
--Deleted the iTunes prefs file.
--Created a brand new user account and tried to start a new library (in the default location) using a sample of my music.
None of these things worked. None would allow me to import my existing music, though only in the original environment did I get the "Damaged Library file" error. All the music was originally imported by iTunes and was living fine in iTunes; I attempted importing by drag-and-drop and via the menu command to Import; and all the music was either ripped from CDs I owned or else was purchased at the iTunes Store, there was no other DRM.
I feel I should delete the iTunes application and re-install it, but I wanted to make sure that there were no untoward risks with doing that: iTunes is an important application as a link between all my data and my iPhone. Has anyone had any success dealing with this issue?

Answer 1

OK, I've come home, I've deleted iTunes and reinstalled it.
I still cannot import any songs.
But I have some new data here: it's evidently only the songs that USED to be in my iTunes library that are no longer importable. In fact, iTunes looks as though it thinks they don't exist. I had a quicktime movie sitting here that I didn't have in iTunes, and it imported fine. Anything I had, though, that was in the library when whatever happened... can't import. Won't play in iTunes if I double-click it. Won't play in Safari.
"Get Info" says they are just fine: MP3 files. But clearly, SOMETHING has happened to them. I'm about to pull my hair out over this.
In theory I should be able to redownload all my purchases from the iTunes Store...BUT for months now (ever since I upgraded to iTunes 7.6.2) I've been unable to contact the Store: every time I try, I get "the server is busy". This is true ONLY FOR THIS COMPUTER...my laptop, using the same network connection, can download everything fine.