I have a computer lab with 18 identical Windows XP machines, of which one will not load gmail on IE8. I've tested this both with "normal" gmail and several Google Apps accounts.
What happens is that it stops on the "Loading" screen and just sits there. I've let it go for over a minute and nothing ever changes. The progress bar on the page shows but is completely empty.
I can load GMail from Safari; it's just IE8 that has the problem. I can load up the plain-HTML version of GMail.
I've also tried adding it to the trusted sites list, but that didn't help either.