I just got a 1.0TB WD Scorpio Blue HD for my MacBook Pro (15", mid-2009) (of course I did research beforehand to make sure the 12.5mm would fit), and it does fit. I used Disk Utility to restore my current hard drive to the new WD drive. Then I opened up my computer, and put in the WD, and tried to boot. Unfortunately, it gut stuck on the gray apple screen with the spinner. So I then booted off my install CD, and repaired disk permissions (there were none), and tried to verify disk. However, verify disk froze up. So I then booted up off my old HD (which was in a USB enclosure). After I booted I noticed that my WD hard drive wasn't showing up in disk utility OR system profile. So I took apart my computer again, and made sure the connection was secure, and tried again, but it still didn't appear. The funny thing is it must appear for a couple minutes (because it'll let me attempt to boot to it), but then it goes away. So I'm basically just asking if anyone has any clue what's going on? Thanks!