OSX10.5.8 MacBook/MacBook Air/MacBook Pro/G4 PowerBook All laptops running HOT! Is Safari 4 the culprit? Or is it Flash? Download MiniUsage and smc Fan Control to monitor the CPU usage/Temperature/Fan RPM differences. Play a youtube video on safari, and from the Safari menu bar, drop down any menu from the bar (File/Edit/View/History/Bookmarks/Window/Help) and leave it dropped. Watch the CPU usage go from 50%-60% down to half, 25%! The heat and fan revs go down, too. Quiet and cool... a bliss.. No more persistent sudden/random thermal shutdowns. So, is it Flash or Safari? For those that tried this method out. Post what you experience and think. P.S. I was blocked from posting in the Official Apple Forum site. My postings were also deleted. So much for... customer feedback or trying to help others.