Today my Mac started giving me the horrible spinny wheel of death every time I try to play a video on sites like Hulu, and collegehumor.com. On Hulu as soon as it gets to the opening commercial (within a few seconds of starting a video) the system hangs, and I have to force quit the browser. This happens in Firefox and Safari, and it's been doing it all day. I'm running Leopard 10.5.6. This is very frustrating--what should I do?