disconnect your usb form iphone. restart your computer. run your itunes. connect usb again should work no problem.
Didn't take much googling. Is this you...? http://www.youtube.com/watch?v=UtaHyocjnTg
The answer is (apparently)Quotedisconnect your usb form iphone. restart your computer. run your itunes. connect usb again should work no problem.