Q: Unfortunately my computer has had some serious probems and crashed several times necessitating reformatting the hard drive. Each time I have restored iTunes and reloaded my music tracks back from my iPod. I have serveral purchased songs which I now cannot play because iTunes tells me I have 5 machines already authorised. I cannot deauthorise these computers as they refer to the same machine that I have had to reformat the drives on. How can I now get this reformatted computer, which iTunes thinks is 5 other machines authorised, enabling me to play my purchased music?
A: The problem here is that when you authorize a computer, iTunes downloads a specific set of authorization keys to that computer in the current configuration. When you reformat the computer, as you’ve discovered, this authorization information is lost, and the iTunes Store thinks that you’re using a completely different computer.
The proper way to avoid this situation is to always ensure that you DEauthorize your computer before reformatting it or reinstalling Windows by selecting Store, Deauthorize Computer from the iTunes menu. This will remove the authorization information from your computer, and reduce your authorization count by one, allowing you to REauthorize the computer after you’ve reinstalled it.
Note that making significant changes to your computer hardware may also require your computer to be reauthorized, using up an additional authorization count. For this reason, always deauthorize your computer before performing major hardware upgrades (such as installing a new motherboard), or taking it in for service.
In this situation, however, since you’ve reformatted your computer, there is no easy way to DEauthorize the individual computer. For users in this situation, however, iTunes does offer the ability to reset ALL of your authorizations once per year. You can find this option on your Apple Account Information page in iTunes, which is found by clicking on your iTunes Store userid which appears in the top-right corner of your iTunes window when browsing the store:
The section under “Computer Authorizations” will indicate how many computers you presently have authorized against this iTunes Store account. If you’ve reached your limit of five computers, a “Deauthorize All” button will appear immediately to the right of this. Clicking this button will reset your authorization count to zero, and you can then manually reauthorize any computers that you are using to play your purchased content simply by selecting Store, Authorize Computer in the iTunes menu.
Note that you can only do this after you’ve reached your limit of five computers, and only once per year. This method is provided as a convenient emergency fix, but should not be considered a substitute for manually DEauthorizing your computer before reinstalling, servicing or upgrading it.