WD My Book Essential 2TB Shuts Down During Backup - Mac MacBook OSX 10.6.8

I have a MacBook (white unibody). I did the formatting required for the drive to work with Mac and have no problems there - when I plug it in to my computer Time Machine starts and it begins backing up. This has happened 3 times in a row - about 5 hours in to my first backup (it complets around 20 gb of 264 gb) and then the drive just mysteriously shuts down. A message comes up on the screen that “backup could not be completed”). 

any ideas why this is happening? I know it is not a power issue because I changed all the power settings on my computer so nothing is shutting it down on this end. 


It is not normal for a disk drive to shut down while in backup duty. i would recommend changing the power adapter and running a diagnostic test using your Apple Mac OS system’s Disk Utility, as instructed in the following link: