I just acquired a powermac g4 quicksilver from a friend..he installed leopard os x on it, but said that he has been getting an error message when the login screen comes on - You need to restart your computer... So I decided to try it and still same thing. I'm not that familiar with macs and error messages...does anyone know what the cause of this is? I tried to reinstall Leopard and it won't even boot up from the DVD. Any suggestions? Thanks for the help!