I have a 24" iMac and am having problems with Safari freezing the whole computer when I go to certain sites. Its inconsistent but, I think Flash ads are the culprit. Bloomberg.com is one site that has done it repeatedly. The whole computer looks like its being shocked by electricity then it has to be hard rebooted. Unpleasant when you have a dozen apps running and work going on. Anybody have any ideas? This occurs almost daily. I haven't seen it happen before in Firefox but, I don't use it as often.