Have sorted on going problem with not being able to sync with iTunes, I was getting lots of warning notices. After a very lengthy conversation with a nice chap at the Mac call centre, he ran through many things, about an hours worth, and determined that i needed to remove some other power drains from my Mac, due to the fact that the iPad draws a lot of power from the Mac to sync, after removing external hard drive and printer we performed a sync and it worked with no problems. Result.