Hi guys, I have a late 2009 MacBook pro 15" with 500GB HD @ 7200 rpm. My hard drive crashed so I got a new 500GB @ 5400 rpm and also a seagate HD (the original one was seagat) then I tried to install snow leopard but neither the installation nor the disk utility could recognize my new hard drive. Even at the system profile, it doesn't appear there. But when I put it into an enclosure at plugged it into USB port the IATA lagoon recognize it normally and I try to install leopard OS onto it, and it just worked but when I put it inside the Mac, it wouldn't recognize it. I tried to use another hard drives, I tried an original Sony vaio 250GB, well it can be recognized also I put the new hard drive into the vaio and it worked there too. Please any one could know what the problem might be?