Sorry to revive this old topic, but I finally found my original Mac OS 9.0 CD and did a clean install of Mac OS 9 on the the G4 Sawtooth. Updated it from 9.0 to 9.0.4 no problem, then from 9.0.4 to 9.1, also without issue. But as soon as I updated from 9.1 to 9.2.1, the freeze problem returned. I went and disabled all of the ATI extensions, and the machine boots into OS 9.2.1 without freezing. However, this doesn't resolve the problem as I need those ATI Extensions since the machine has an ATI Radeon 7500. What should I do now?