Authorizing iTunes to transfer purchases

Question

I am kinda freaking out here because we just got a new computer and I want to transfer all my purchases to my new library but it won't let me.
It says this once I type in my account name and password to authorize:
"You cannot authorize more than 5 computers. You have already authorized 5 computers with this account. To authuroize this computer you must deauthorize one of the other computers."
This doesn't make any sense whatsoever since I have only had 2 computers and this new computer being the 2nd.
PLEASE HELP ME! Is it because of Windows Vista?

Answer 1

If your system crashes or you reinstall your operating system without deauthorising iTunes first, even a single computer can use up your limit of 5 authorisations. You can't deauthorise those dead installations individually. If you've reached your limit of 5 you have the option to deauthorise them all in one go from your iTunes Store account and start over again. *Just note that you can only use this option once a year*: About iTunes Music Store Authorisation and Deauthorisation
To deauthorise all computers associated with your account:
1. Click iTunes Store in the Source pane.
2. If you're not signed in to the store, click the Account button, then enter your account name and password.
3. Click the Account button again (your ID appears on the button), enter your password, and then click View Account.
4. In the Account Information window, click Deauthorize All.
See also this article: One computer using multiple iTunes Music Store authorizations