Here is something that I have never seen before... I have four external FW800 Seagate drives, two 500GB, and two 1.5TB. The 500GB's, "Gold" and "Silver," are daisy chained and connected to my Mac Pro's FW800 port. The 1.5TB drives, "Black" and "White," are daisy chained and connected to the other FW800 port. The issue: After coming back to my mac after a day or two, Black and/or White are missing in the finder. I'll go into my disk utility and they are unmounted, but disk utility says that Black/White is Gold/Silver.... and if I repair it tries to repair but then nothing. The only way to fix it is to reformat. I have never seen this... why would at 1.5TB drive unmount then take on the property of a different 500GB external drive? Using Mountain Lion.