There's a major bug in Safari 5. I've never encountered this problem with previous versions >>> If I start my Mac Pro and open Safari I can load streaming videos (like YouTube) without any issues for a while. Then suddenly videos don't load anymore (they don't even hang...it's just a black field). The only solution is to restart the computer or close and open the browser in order to watch streaming videos again. I've read other user reports who have the same problem.