Lion, early 11 MBP. Ok, so i gave up on the last issue [wouldnt back up] erased the external HDD to try fresh. Now it tells me it needs 536 GB to back up??? I have a 500gb hdd in the MBP? WTF?? DO i really need to get a bigger external HDD to do this? Thanks. Kind of worried, because all the family pics are on the MBP and now i have no backup at all!!!