I have been having this problem for a while so I thought a clean install with Tiger would help but it hasn't. Whenever I set the machine to sleep it nips right off but no longer sends a signal to the monitor to sleep and or wake! It used to be that the monitor would fall right asleep next to my G4 but no longer. I switched monitors with my wife who has never had a similar problem with her G4, and the same thing keeps happening! Brand new clean install of Tiger just 2 days ago, and still the same problem as before. Haven't found a thing searching the forums, anyone have any idea? Thank you!