Can't access any songs after reinstallation of iTunes

Question

Not very good with computers or anything, so please be gentle.
I got stuck with the whole Version 5 bug and had to re-install my iTunes software in order to be able to use it. I got through that okay, but now I have another huge problem.
Every time I try to listen to one of the songs that I bought off at the music store before I had to reinstall iTunes, a message pops up saying that I'm not authorized to play that song on this computer (which seems impossible, as I downloaded the song on this computer in the first place, but you know, whatever). It tells me to log on in order to authorize the playing of the song and when I do, it redirects me to a screen in the Music Store that tells me to "please downoad version 5," which obviously I really do not want to do as that's what screwed up my iTunes in the first place. Then when I try to go back to the song to actually play it, thinking I must have authorized it by now, it tells me the song STILL isn't authorized.
I've tried this with more than one song and none of them work. I've also tried to use the music files I coped for back-up, just in case something went wrong during reinstallation, but those songs won't play either. I could redownload them all but that would be too much money for songs I already paid for in the first place.
Am I doing something wrong, or does Steve Jobs just hate me?
Pleeeeease help. I really, really want my music back. ;(\
Oh, and if it helps the problem any, my Ipod is a mini and my iTunes is version 4.6, I think. Not sure if that information is necessary but I thought I'd mention it anyway.
EDIT: Okay, I checked what Apple actually has to say about this whole authorization thing. IT says the problem is probably that I have too many computers authorized to play the song, but I know that absolutely cannot be the case, as I only use one computer with my iTunes.
Is there a way to check how many computer iTunes thinks the song is registered with? because maybe it thinks there's more then five when there's really only one.

Answer 1

You've probably already got things figured out by now, but since I just saw your post, and the same thing happened to me, I figured I'd tell you how I fixed it just in case. My instructions are kind of long, but I wrote them up for me this way in case it happens again.
1.     If you just authorize again, like it asks you to do, you will probably use up 2 of the 5 authorizations that you’re allowed. (You’re only allowed to play your purchased music on 5 computers. If you get a 6th computer, you have to de-authorize one of the others. If you sell your computer, you should de-authorize it first while you still have access to it or you won’t be able to.)
2.     Quit out of the error box, without authorizing.
3.     Click on ‘Music Store’ in your Source column.
4.     Click once on your account name; under the eye, to the right of ‘Account.’
5.     A box comes up asking you to enter your password for your apple id.
6.     Enter your password, then click on ‘View Account’.
7.     The screen that comes up will tell you how many computers you currently have authorized to play your purchased music.
8.     If it says: “Computer Authorizations: One machine is authorized to play music purchased with this account”, then something is wrong because it obviously isn’t letting your one machine play music.
9.     So, you need to go ahead and de-authorize your machine and reauthorize it to keep it from using up 2 authorizations.
10.     Click on ‘Advanced’ on the top menu bar of Itunes, and then ‘De-authorize Computer…’.
11.     Make sure the top radio button is selected, next to De-authorize Computer for Music Store Account.
12.     Click ‘OK’.
13.     Then go back and repeat steps 3-7, to look again to see how many computers you have authorized. It should now say ‘0’.
14.     Then, try to play one of your songs that was purchased. You can always click on the ‘Purchased Music’ link in the ‘Source’ column to find all of your purchased music.
15.     The same box will come up asking you to authorize your machine. Go ahead and do it now because now it will only cause one computer to be authorized.
16.     You only have to do this on one of your purchased songs. All the rest of the purchased music will work after that.