My wife has a powerbook g4 15" and last night she was coping some of her files to an external hdd and when doing so moved or deleted (I'm not sure) some system and library files. Now when you try to boot it goes straight to a gray screen with a broken/happy folder. I tried formatting from a usb external hdd (tiger and leopard) but couldn't get it to show. I don't think it will boot from usb. So I tried to load Leopard (it is on a DVD+R DL) but the cd drive spits it out. So I guess it can't read +R DL discs. I tried formatting from my Tiger DVD-R but still spits it out. I have also tried formatting from my Tiger CDs (4 CD-R's), but it still spits them out. I have tried every startup shortcut. The startup manager comes up, but it is blank (doesn't even show a harddrive) with just a refresh and arrow button. The only thing I can get to is Open Firmware. We had no problems with this computer till last night. We have had no problems with the optical drive before either.