Recently bought a mac pro Quad core (2009), running 10.8.2. I de-activated my Photoshop CS3 from my G5 and installed on the Mac Pro, but it would not activate. I called Adobe, they said it would not work on 10.8.2. I thought maybe I could install 10.5 from the original disk on another hard drive and start up from that drive when using Photoshop, but I have not been able to get the 10.5 to load. It always goes to 'You need to restart' window. Does anyone have any ideas how to work around this problem?