I've linked an article that details a number of steps that can be followed in order to restore a connection to the iTunes Store on your PowerBook.
You may be completely unable to access the iTunes Store on your computer or iOS device. You might also see an alert message similar to one of the following:
- "Cannot connect to the iTunes Store. An unknown error has occurred."
- "We could not complete your iTunes Store request. The iTunes Store is temporarily unavailable. Please try again later."
- "iTunes could not connect to the iTunes Store. Make sure your network connection is active and try again."
This article will guide you through the basic troubleshooting for the iTunes Store.