I am trying to backup to an external hard drive, 120gb. The backup starts fast and then hangs at 57%. I have let it run for several hours and still only 57%. I have a new hp p6350z pavilion computer with a 454 gb with 420 gb free. The external hard drive has been reformatted prior to attempting the backup. All of the literature I have found does not say that the backup hard drive must be equivalent to the computers hard drive.