I have four hard drives installed on my Mac Pro. One is the 640 GB drive that came with it, one is a 500 GB drive and there are also two 1.5 TB drives. However, when I go to select the Scratch Disk in Illustrator CS5 it only lists the Start-up disk and Time Machine as my Scratch Disk options. What gives? Photoshop shows all of the hard drive options for Scratch disks.