Backing up iPhone 4 and iPad problem

Hi everybody,

I have a friend who has a MacBook pro referbished, iPad 3G, and iPhone 4. When a device is plugged into the computer, even my 3GS, iTunes begins to back up but then freezes, the rainbow stays forever and iTunes (not responding). All software is up to date, I backed up all the music in iTunes, removed iTunes from the computer, then reinstalled it and..... Same problem, when backing up any device, iTunes freezes. Any suggestions on what the problem is or better yet a solution?