Can't sync iPhone after iTunes update
After updating iTunes to the latest version two days ago, I can't sync my iPhone 5 because the system claims I don't have access privileges to back up to my iMac's main drive.
But I do: I've checked and triple checked my access to the drive; I even changed "Everyone" to "Read & Write," just to be sure. Still iTunes can't perform the the first step of syncing (backing up the iPhone).
Any ideas on what I should try next?
Thanks!
PS: Also, when this happens, clicking the Cancel Sync button leads to the "Cancelling..." message, but then hangs there. The only way I can get out is to do a force-quit on iTunes.
iMac (21.5-inch Late 2009), OS X Mountain Lion (10.8.2), 4 GB RAM