When I check this in IE 8 in Vista 32bit I can see what looks like another page partially loading, then you are almost immediately sent to the other page. I think it may have to do with the way you are redirecting the user. Is there some intermediate page that the user goes to first when they enter the site? What happens if you go to the other page directly?
Based on how quickly it happens it may be due to some image loading. There are ways you can preload the images to force the page to download the images before attempting to load. There are some good references online for preloading the images if you are interested in trying this approach.