the iPhone could not be synced because this computer is no longer authorised for purchased items that are on this iPhone
This happed to me just now, yesterday is still fine, but then it does not sync anymore just now. I've tried deauthorize and authorize again but DID not solve this problem.
I am using:
iTunes 11.1 on
mid-2011 macbook air running OSX 10.8.5
&
iPhone 5 A1429 32G running iOS7
iPhone 5, iOS 7, itunes 11.1 for mac