I never had my mac pro lock up until installing Perian (among other things simultaneously). I have had 3 lock-ups since then. Two of them were in Safari watching a flash video. The other was also in Safari and I think I had a flash video loading in the background, but I don't remember 100%. In all of these cases Safari became unresponsive and then everything else too. The dock would not magnify when hovering the mouse over it. Nothing was responsive except the mouse. Any ideas? This was Perian 1.1.