I just bought a powermac g3 and am trying to install tiger through the 4 cd's. I try installing it by double clicking the disk and it brings up a screen to restart the computer to install os X, but when I click restart it says "An error occured. Startup disk was unable to select the install disk CD as the startup disk. (-2)" I also tried restarting it on my own and holding down the "c" key, but that only left the screen in grey. Any help?