I will be playing videos on you tube and CPU for Safari shows 100 in activity monitor. Fans will run at 4500 RPM and CPU Temp 160F. I will leave Safari open and stop searching and it will maintain this state indefinitely even with computer doing nothing. I will then shut down Safari and temps and fans immediately go down to normal idle state with 20 seconds. I can immediately re-open safari and CPU is normal at 1-2 and everything remains normal. Has happened 3 times since Leopard 10.2 update and I think before and after Safari 3.1 update What is going on here?