My ipad 2 spontaneously has stopped talking to my MacBook Air. Despite multiple rebooting of both devices, and replacement of USB cable, when i plug in ipad, it launches iTunes, but then i get the spinning beachball. Once this occurs, i can also no longer successfully power down the ipad ... the spinning widget spins and spins ...forces me to do a reboot of the ipad to recover. I am stumped and appreciate any help.