My wife and I both have an iphone 4. From the beginning, we've had a problem syncing the phone with itunes. When I plug the cable connecting the phone with the USB in my MacBook Pro, with itunes open, either nothing happens or a sync will begin and suddenly terminate before completion. Usually, after several trials, I manage to get a sync. I wonder whether this has anything to do with the connecting cables we are using. When we got the iphone 4 we did not separate the new cables from those we used with our iphones 3gs, assuming there was little difference, and we use them indiscriminately. Could this be the cause of the problem?