itunes says my computer is no loger authorized to play/sync music bought on my account. Suddenly is not recognizing updated email address.

Late last year (I believe) I updated the email on file for my itunes account, so that the one on file would be my most up-to-date current email. I have had no problems until now, when, trying to sync my most recently purchased music album to my ipod, a pop up happened saying that my computer was no longer authorized to play music bought with this account, yada-yada, and unless I signed it and r-authorized it, 400+ songs would be removed from the ipod. The original address was what appeared auto-filled. It obviously doesn't work, and while I was able to sign in (multiple times) with my current one, it wouldn't do anything. It IS the same account... when I went to the account page, I could even pull up a list of all the purchases made since 2007. And of course the apple/itunes tech "help" is crap, and I can't get assistance without PAYING the idiots 29$. Any input? As far as I can tell, those tracks were taken off my ipod, as I couldn't DO anything without another popup happening again and again and again, until I just exited out of it enough times.

-Louisa