I have a G4 with os 9.2 and It freezes up after 25-40 minutes of use. When you try to reboot from the button on the machine it will reboot but everything will still be frozen. The only way out is to turn off the power for a few seconds and then start up again. The funny thing is when it freezes up the power light goes out on the computer. I talked to Apple anf they want me to take it in for service. Any ideas? I tries to change energy controls even turned of that extention. I rebuilt desktop / zapped the PRAM. I'm out of ideas HELP !