This happens to me on a terminal server I use. It’s got 4 gigs of ram and there are usually only 8 people on it. I’m assuming that it’s something in the java/css encoding that makes it slightly unstable on my machine.
I can’t power-browse digg because as I try to open multiple upon multiple tabs the machine locks up. My firefox will eventually lock up if I try to do this too much but typically I have to force it closed.
(as an aside) Sometimes on digg, when I open up buried comments, the machine locks up for a minute.