Uhhh my brothers imac has not been starting up. Its booting up but freezes at the screen with the grey apple in the middle of the "white". i have tried booting off a disc. But the keyboard and mouse stop working about 5 seconds into the start up. I can get in to single user mode but thats about it. Its G3 not sure if that matters. Its on tiger operating system. So yeah any help will be greatly appreciated.