Hi, My 4 months old Mac Pro's logic board was recently replaced. After getting the unit home, it would 'see' my hd on bay 2. I transferred it to bay3 and 4 and it's the same thing. When I placed my data hd on bay 1 and the system hd on bay 2, it booted off my external firewire bootable drive and is able to 'see' my data hd but not the internal system hd. Any idea what's wrong with it? I've already taken it back to Apple and will know in a day or two but just want to know if anyone had the same problem. Thanks.