I'm trying to upgrade my hard drive, but my macbook will not boot to the new hard drive. I have erased and cloned the hard drive about three times now. It won't boot while it is in the macbook and it won't boot from an external hard drive case. All I get to is the screen with the mac logo and the spinning wheel. I have made sure the drive is GUID formatted, but it still doesn't work. When I put the new drive in an external case and plug it into my macbook I can see and access everything on the drive. Can somebody please tell what I am doing wrong? By the way the new drive is a WD 500gb Scorpio Blue.