My Mac Pro, used very little as yet in this life following a fortuitous acquisition from my former company, is failing to recognize one of the three hard disks. I have a 320 gb system disk running Snow L, and two 500 gb disks which are currently empty of data. Following boot, the second of the 500 gb drives isn't available - it doesn't appear on my desktop, or in Finder, or in the side bar when I launch Disk Utility. The system profile information returns a single line saying there was an error when trying to detect information about my disks - it doesn't give me information on any of them. In its previous life this disk was a mirrored RAID array (with the other 500 gb drive) used a shared file server for standard office documents etc in what I would call a modest load environment - it was no media studio! Any thoughts? Thanks.