Imac G4 Won't Start And Do Not Wake Up From Sleep



After installing Tiger.. the iMac start to have kernel panics and to don't wake up from sleep. Also I have to start up two times ( sometimes three) because at first startup the iMac stays forever in a white screen just after the dimmed white screen with the rolling sign.

I reinstalled Tiger from scratch erasing the disc
PMU reset
PRAM reset
all kind of permissions, prebindings, crons, diswarriors and techtool

If I disconnect the sleep time (to never) the computer works perfectly. As soon as the imac goes to sleep it wakes up but just after the finder appears the computer freezes. but not completely because you can access the computer from another computer on the network.. but the imac in itself only can be shutdown.

I also tried starting up with another disk (firewire) that works perfectly in other computers have the same behavior on the iMac.

thanks in advance