ITunes does not authenticate, even though it gives message that it does

Question

The story so far – in detail.
One day, over a year ago now, my iPod would not synch properly with my iTunes and I got a message telling me some of the songs were not authorized. The iPod locked up and had to be rebooted/reinstalled at the apple store and they told me it was dying.
{As it turned out, it was my laptop that was dying – the motherboard would no longer see half my memory and the firewire 400 was intermittent, which must have caused the iPod to freak out, because I’m still able to use the iPod a year later, but I never plug it into the firewire 400 on this laptop.} This did not fix the inability to move the music, which coincidently (the store and on-line support did not indicate a link) happed around the same time.
Some extra background details are needed here to help frame the issue.
The original music on all my computers was purchased on three different iTunes accounts for various reasons, including multiple moves. (This is why I would really like an account column in the view options)
This is not my original laptop, my wife is not using her original iMac. We have upgraded and transferred all our files, but the problem came long after that time (years).
My wife’s iMac is home to the original, albeit transferred, files. All the music authorizes and works fine on her computer. It is a G5.
The music will not work on my computer (Powerbook G4) or my sons’ computers (Intel Duo Macbooks).
When I try to play the music, I get the not authorized pop-up and it tells me to enter the password to authorize. I enter the correct password and I get the new pop-up that tells me I have successfully authorized the music, but it doesn’t start playing as it normally should. I click on the now (supposedly) authorized song again, and I get the same not authorized message. Any second, or subsequent time through this loop yields the same results, but at least the number of authorized computers remains correct.
Between the on-line help and the store I have been asked to do the following, and have complied:
Deauthorize and reauthorize the music files.
Deauthorize and reauthorize all my music accounts (on-line help performed the deauthorization on all the accounts I thought I had, turns out I have one more, but it never had a problem).
Uninstall/remove iTunes from the offending computer and reinstall it.
Throw away the offending music files and re-add them.
Put all my music on my wife’s computer, put it on an iPod, remove the music from my computer, re-add all the music from the iPod.
Re-install my OS, with a reinstallation of iTunes and re-add all the music.
Find a backup copy of the music saved to my external hard drive and reload it.
Load the music on other computers and see if they will authorize.
None of the above (an probably some I am forgetting) worked, so I decided to take a break from the frustration and just wait and see if some future iTunes upgrade would fix the problem in the same mysterious way it appeared. You may have guessed by my writing in this forum that there was no joy on that coarse of action. So here I am for one more attempt with the vain hope that after a year someone else has had this problem and someone has figured out how to fix it.
If, or likely when, no one can provide a fix this time, I would like to propose a solution with consideration for the year of being unable to access songs I legally purchased.

Answer 1

Hey Caseyb1tx,
I'd take a look at the following two articles to see if they can resolve the issue you're experiencing:
iTunes: Downloading iTunes for Windows using Internet Explorer
http://support.apple.com/kb/TS3212
Trouble installing iTunes or QuickTime for Windows
http://support.apple.com/kb/ht1926
The File Download window will ask you to Run or Save the iTunes file you are downloading, try choosing each option to see if one works over the other - if you Save it, the iTunesSetup.exe file is saved onto your computer, so look where it is saving to and open the file from there to install iTunes.
Have a good one,
David