I have an early 2011 Macbook Pro which has been running fine up until a month ago when it became unresponsive the second it was turned on, immediately getting rainbow wheel. Safe mode however worked fine. I booked an appointment at the Genius Bar and went to back up my Mac with Time Machine, only to find that my hard drive had stopped working and all my old back ups on there were lost. I took it to the Genius bar and the 'Genius' spent around an hour and a half running diagnostic tests and trying to get to the bottom of why my Mac was being unresponsive. He couldn't figure it out and told me that the only course of action would be to buy a new hard drive, use time machine to back it up and then reboot my Mac. I went about doing this, getting a new 1TB WD 2.5inch hard drive and then entering my user in safe mode and starting time machine. However after completing about 250GB of the 290GB I get this error message, 'The backup was not performed because an error occurred while copying files to the backup disk. The problem may be temporary. Try again later to back up. If the problem persists, use Disk Utility to repair your backup disk' Any support would be great.